| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: Fix slab-out-of-bounds when handling team device events
The mlx5_handle_changeupper_event() and mlx5_handle_changeinfodata_event()
functions check for LAG masters (which includes both bonding and team
devices) but only call bonding-specific APIs. When processing team device
events, calling bond_slave_get_rcu() and bond_is_slave_inactive() on
team_port structures causes KASAN to detect an out-of-bounds memory access
since team_port is smaller than bond slave.
Fix this by wrapping the bond-specific API calls with a check for bonding
devices. This allows the function to still process LAG events for both
bonding and teams but only calls bond-specific functions when dealing with
actual bonding devices.
For mlx5_handle_changeinfodata_event(), keep the explicit bond check as
mlx5 doesn't handle state information for team ports anyway.
Tested with Mellanox ConnectX-5 on Linux 7.2.0-rc6:
- Bonding: PASS (no regressions)
- Team device: PASS (no KASAN errors) |
| In the Linux kernel, the following vulnerability has been resolved:
octeontx2-pf: Fix aura BPID assignment when CONFIG_DCB is enabled
Previously, BPID assignment under CONFIG_DCB assumed
`queue_to_pfc_map` was always initialized. For SDP VFs this leads to
invalid memory access as it was not initialized.
This patch adds a NULL check for `queue_to_pfc_map` before
dereferencing it. Also, simplifies the logic by always assigning a
default BPID first, then conditionally overriding it if CONFIG_DCB is
enabled and the map exists. |
| In the Linux kernel, the following vulnerability has been resolved:
tipc: prevent GCM nonce reuse on peer key changes
TIPC can encrypt traffic between nodes using a different transmit key
for each node. In this mode, the AES-GCM nonce for a packet sent to a
known peer consists of a 32-bit prefix (a per-key salt XOR the peer's
address) followed by a 64-bit counter. That counter is stored in the
peer's RX crypto object. When the peer reports a change in which key
it uses to receive packets, TIPC resets this counter. The sender can
still be using the same TX key and salt, so subsequent packets reuse
earlier nonces. This nonce reuse breaks confidentiality and exposes
GCM's authentication key. This makes forgeries trivial: an attacker
can exploit CTR malleability to alter captured ciphertexts and use the
recovered authentication key to compute a valid tag for the modified
ciphertext, under the same key and nonce.
Use the TX key's existing aead->seqno counter instead. All encryptions
using that key object share the same atomic counter, so concurrent
encryptions get distinct nonce counter values. The counter survives
key activation and peer reconnection, and peer key-status reports
cannot reset it. This prevents those transitions from causing nonce
reuse while the same TX key remains installed.
The nonce format is unchanged, and receivers do not require consecutive
counter values, so sharing the counter across peers remains compatible
with existing receivers. A pre-existing check still invokes key
revocation in the unlikely event that the counter wraps to zero. |
| In the Linux kernel, the following vulnerability has been resolved:
net: page_pool: fix use-after-free in page_pool_recycle_ring_bulk()
With CONFIG_PAGE_POOL_STATS=y, page_pool_recycle_ring_bulk() updates
the recycle stats after dropping the producer lock. If it just recycled
the last inflight netmems of a pool being destroyed, page_pool_release()
can pass its producer-lock barrier and free the pool before
recycle_stat_add() runs.
Commit fcc680a647ba7 ("page_pool: allow mixing PPs within one bulk")
moved this stat update after the unlock. Commit 271683bb2cf32
("page_pool: Fix use-after-free in page_pool_recycle_in_ring") later
added the barrier, but only fixed page_pool_recycle_in_ring(). Move
the update back under the lock. |
| In the Linux kernel, the following vulnerability has been resolved:
net: stmmac: fix rx Scatter-Gather support
When a received frame is larger than dma_buf_sz, the DMA scatters it
across multiple RX descriptors (rx Scatter-Gather). The secondary RX
buffer (sec_page) was only allocated and programmed when split-header
(SPH) was active, so for regular frames buffer2 was neither allocated
nor backed by a valid mapping. As soon as an incoming frame overflowed
buffer1, the DMA wrote the overflow into the unmapped secondary-buffer
address, triggering an SMMU translation fault on IOMMU-based platforms:
arm-smmu 15000000.iommu: Unhandled context fault: fsr=0x402, iova=0x00000000, fsynr=0x7f0011, cbfrsynra=0x1c90, cb=11
arm-smmu 15000000.iommu: FSR = 00000402 [Format=2 TF], SID=0x1c90
arm-smmu 15000000.iommu: FSYNR0 = 007f0011 [S1CBNDX=127 WNR PLVL=1]
Enable scatter-gather for non-SPH frames on cores that can program an
independent secondary RX buffer (GMAC4/XGMAC): allocate and mark buffer2
as valid in stmmac_init_rx_buffers() and stmmac_rx_refill(), and account
for it in the buffer length computation. Legacy cores have no set_sec_addr
op, so they keep buffer2 disabled.
Since buffer2 is handed to the DMA at page offset 0, the page pool sync
window is widened to cover both buffers in every mode: offset is set to 0
and max_len to dma_buf_sz + stmmac_rx_offset().
The FCS can straddle the buffer1/buffer2 boundary and a descriptor
boundary, so it is now stripped from the tail of the assembled frame with
pskb_trim() instead of from a single buffer, avoiding an unsigned underflow
for frames that overflow a buffer by 1..3 bytes. For single-buffer frames
the XDP program must not see the FCS, so it is removed from the XDP buffer
before the program runs.
Native XDP currently only supports single-buffer (linear) frames. An
oversized frame accepted by the MAC (jumbo enabled) is received via
buffer2; the XDP program only sees buffer1, so on a TX/REDIRECT verdict
the frame is forwarded truncated. XDP multi-buffer support to handle
this case is planned as a follow-up.
AF_XDP zero-copy RX is not covered by this change: a ZC queue still
programs buffer2 at DMA address 0 (and XGMAC has no buffer2-valid bit),
so an oversized frame overflowing buffer1 can still trigger the same
SMMU translation fault. Handling is planned as a follow-up. |
| In the Linux kernel, the following vulnerability has been resolved:
seg6: ensure packet data is writable before modifying SRH and IPv6 DA
advance_nextseg() modifies the SRH Segments Left field and the IPv6
destination address without ensuring the packet data is writable.
seg6_next_csid_advance_arg() has the same problem when it advances the
NEXT-C-SID argument in the destination address.
The skb may be cloned, for example by an AF_PACKET socket receiving on
the ingress device. advance_nextseg() and seg6_next_csid_advance_arg()
then write into the packet data shared with the clone. A read from that
socket can return the modified packet instead of the received one. The
simplified path below shows this for advance_nextseg():
__netif_receive_skb_one_core
__netif_receive_skb_core
deliver_skb [orig: users=2, cloned=0]
packet_rcv
skb_clone clone queued to the AF_PACKET socket
consume_skb(orig) [orig: users=1, cloned=1]
ipv6_rcv
ip6_rcv_core skb_share_check: no-op [orig: users=1]
[...]
input_action_end_core
advance_nextseg writes into the data shared with the clone
Call skb_ensure_writable() in advance_nextseg() and in
seg6_next_csid_advance_arg() before they modify the packet data.
skb_ensure_writable() may reallocate skb->head, which invalidates the
pointers into the packet data taken before the call.
advance_nextseg() now returns a valid SRH pointer, or NULL if
skb_ensure_writable() fails.
seg6_next_csid_advance_arg() takes the pointer to the destination
address from the skb after skb_ensure_writable().
On failure, the callers drop the packet with SKB_DROP_REASON_NOMEM. |
| In the Linux kernel, the following vulnerability has been resolved:
net: restrict SO_RESERVE_MEM to TCP sockets and cap max value
Commit 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM") and
commit d00c8ee31729 ("net: fix possible NULL deref in sock_reserve_memory")
only checked sk_has_account(sk), which is true for both TCP and UDP
sockets.
However, SO_RESERVE_MEM and sk_unused_reserved_mem() are currently only
supported by TCP:
- On UDP sockets, sk->sk_forward_alloc is protected by
sk->sk_receive_queue.lock, whereas sock_reserve_memory() and
sock_release_reserved_memory() only acquire lock_sock(sk). Concurrent
UDP packet reception/release and setsockopt(SO_RESERVE_MEM) corrupt
sk_forward_alloc and memcg accounting.
- udp_rmem_release() reclaims excess sk_forward_alloc without
accounting for sk_unused_reserved_mem(sk).
Restrict sock_reserve_memory() to TCP sockets (sk_is_tcp(sk)) for now.
Supporting SO_RESERVE_MEM for UDP (acquiring sk_receive_queue.lock and
honoring sk_unused_reserved_mem() in udp_rmem_release()) can be done in
a future net-next series if needed.
In addition, reject val > SZ_1G with -EINVAL in
sk_setsockopt(SO_RESERVE_MEM). Without an upper bound, values near
INT_MAX cause sk_mem_pages(delta) and (pages << PAGE_SHIFT) to overflow
32-bit signed int, corrupting sk->sk_forward_alloc and
sk->sk_reserved_mem. Using a page-aligned cap (SZ_1G) ensures that the
page-rounded sk->sk_reserved_mem reported by getsockopt(SO_RESERVE_MEM)
can always be passed back to setsockopt(SO_RESERVE_MEM). |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Wait for an RCU tasks grace period before freeing trampoline progs
When a prog is detached from a trampoline, it is freed after an RCU
grace period, or an RCU tasks trace one if it is sleepable. This covers
the tasks that are running the prog, since the prog's enter helper takes
the matching read lock before the prog is called. On a preemptible
kernel, it doesn't cover a task that was preempted in the trampoline
just before the enter helper. That task holds no lock yet, and it calls
the prog after it was freed:
BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_enter_recur+0x3a5/0x3f0
Read of size 8 at addr ffffc90000055040 by task candidate/110
CPU: 1 UID: 0 PID: 110 Comm: candidate Not tainted 7.3.0-rc2-00014-g15071f2a1263-dirty #2 PREEMPT(full)
Call Trace:
<TASK>
__bpf_prog_enter_recur+0x3a5/0x3f0
bpf_trampoline_6442509193+0x37/0xf1
__x64_sys_futex+0x9/0x410
do_syscall_64+0xb0/0x530
...
Wait for an RCU tasks grace period before the existing one when freeing
a prog that was linked to a trampoline. An RCU tasks grace period only
ends once the tasks that were preempted have run again, and
bpf_tramp_image_put() already relies on it to free the image. It doesn't
wait for tasks that sleep in the trampoline, the next commit takes care
of those.
Only progs that were linked to a trampoline can be called this way, so
bpf_trampoline_add_prog() marks them and other progs are still freed as
before. |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Skip detached progs in trampoline images that are still in use
bpf_tramp_image_put() makes sure a trampoline image is not freed while
a task may still be running in it, but nothing similar is done for the
progs called by that image. Detach drops the last prog reference right
away and the prog is freed after grace periods, on the basis that a
task still in the traced function skips the fexit progs once the nop at
ip_after_call is patched to a jump.
That leaves out a task sleeping in a sleepable prog that runs before
the detached one, which no grace period waits for:
CPU 0 CPU 1
in image I, sleeping in prog S
detach P from I's trampoline
-> new image, bpf_tramp_image_put(I)
bpf_prog_put(P), last ref
grace periods, P freed
back from S
__bpf_prog_enter(P)
call P->bpf_func
If S and P are fexit progs the task is already past the patched jump,
and fentry only images don't have one. On x86 this is an int3 in
poisoned bpf_prog_pack memory:
Oops: int3: 0000 [#1] SMP NOPTI
CPU: 18 UID: 0 PID: 94573 Comm: x169 Not tainted 6.18.44 #1 PREEMPT(lazy)
RIP: 0010:0xffffffffc0601d8d
Call Trace:
<TASK>
? bpf_trampoline_6442515411+0x1a4/0x21b
bpf_lsm_bprm_committed_creds+0x5/0x10
security_bprm_committed_creds+0x5f/0x70
begin_new_exec+0x2d6/0x410
...
We hit this in production when progs attached through trampolines got
detached while their hooks were busy, and it was independently found
with a fuzzer and KASAN.
Have the JITs emit a patchable nop in front of each prog call sequence
and record it in the image. When a prog is detached, patch its nop to a
jump over the call sequence. Progs that stay attached keep running for
the tasks that are in the image, and ip_after_call isn't needed anymore.
The task can be in any image that isn't freed yet, not only in the
current one. It sleeps in image I1 that calls S, P and Q, then P is
detached and the trampoline moves to image I2, then Q is detached and
its call is still in I1. So the trampoline keeps a list of its images
until they are freed, and detaching a prog patches its nop in all of
them. Images hold a reference on the trampoline for that long.
On riscv and loongarch a jump of any range takes several instructions,
and a task preempted in the middle of them could resume into half of the
new sequence. The nop is a single instruction there, patched to a near
branch through arch_bpf_trampoline_skip().
With the extra nops, BPF_MAX_TRAMP_LINKS progs no longer fit in a page
on x86 and arm64 (and already didn't on powerpc), so lower the limit
there like s390 does. |
| In the Linux kernel, the following vulnerability has been resolved:
net: bcmgenet: fix NULL dereference in set_coalesce before first open
The Rx ring priv and index are only set in bcmgenet_init_rx_ring(),
which runs at open. Setting the Rx coalescing parameters on an interface
that was never opened, e.g. "ethtool -C eth0 rx-usecs 50", dereferences
a NULL ring->priv. The oops happens with RTNL held, so networking
stays stuck until a reboot:
Unable to handle kernel paging request at virtual address 0000000000002788
pc : bcmgenet_set_rx_coalesce.isra.0+0x10/0x88
lr : bcmgenet_set_coalesce+0xe8/0x180
Call trace:
bcmgenet_set_rx_coalesce.isra.0+0x10/0x88 (P)
__ethnl_set_coalesce.isra.0+0x490/0x570
ethnl_set_coalesce+0x48/0xc0
ethnl_default_set_doit+0xf4/0x230
genl_family_rcv_msg_doit+0xe8/0x160
genl_rcv_msg+0x220/0x2a0
netlink_rcv_skb+0x68/0x140
genl_rcv+0x40/0x60
netlink_unicast+0x338/0x3c0
netlink_sendmsg+0x19c/0x3f8
__sock_sendmsg+0x64/0xc0
__sys_sendto+0x124/0x198
__arm64_sys_sendto+0x30/0x48
Set priv and index at probe. Writing the registers while the interface
is down is harmless because open resets the MAC and
bcmgenet_init_rx_coalesce() reapplies the stored values.
It was observed on a Raspberry Pi CM4, but should apply to all other
genet devices. |
| In the Linux kernel, the following vulnerability has been resolved:
net: cap skb->queue_mapping when the tx queue is picked
skbedit can set skb->queue_mapping and raise the per-CPU skip_txqueue
flag so __dev_queue_xmit() honours the mapping. __dev_queue_xmit()
cleared the flag before sch_handle_egress() and only read it afterwards,
so the flag was not confined to the xmit that set it: a nested xmit
(mirred redirect or mirror, or a drop after skbedit) could set the flag
and the outer xmit would consume it for an skb that never went through
skbedit.
A forwarded packet still carries the ingress NIC's rx_queue + 1 in
skb->queue_mapping, so the outer device then indexes its tx queue state
with that stale value. Taprio's child array q->qdiscs[] is sized to the
device's queue count, so taprio_enqueue() indexes past its allocation
and dereferences the result as a struct Qdisc *.
We (ab)use the skb->nf_skip_egress which means "skip netfilter egress
for this packet" to tag to "am I in tc egress?". Despite the overload
I dont see it as a conflict since the marker is set only around the
single sch_handle_egress() call and ingress path is guarded by
tc_at_ingress.
I will send a followup(net-next) patch once this hits net-next to
rename the skb->nf_skip_egress bit/flag to skb->skip_egress
Arm the flag only from the egress classifier that can use it: raise
skip_txqueue from tcf_skbedit_act() only when it runs inside
sch_handle_egress(), thanks to skb->nf_skip_egress. An egress qdisc
classifier runs in q->enqueue(), after the tx queue has been picked,
so a mapping it sets cannot affect the current packet; arming the flag
there only pollutes it for a later xmit. Then own the flag for the xmit
frame the egress hook runs in: save the incoming value and clear it just
before sch_handle_egress(), and restore it after the hook - on the
consumed (drop) path, or, in the same call that reads it, on the
surviving path. The save and the restores stay inside the
egress_needed_key static branch, so a packet pays for them only when
egress hooks are active (2f1e85b1aee4).
Store the value netdev_cap_txqueue() selected back into skb->queue_mapping
in netdev_tx_queue_mapping(), as netdev_core_pick_tx() already does, so
the skip_txqueue path never hands a later reader on the xmit path a
mapping the device cannot serve. A store made still later in the same
frame, by a tc BPF program attached to a transmit qdisc, is outside this
path and is not re-capped; a separate followup will resolve that path.
netdev_xmit_skip_txqueue() returns the previous flag value so the
save-and-clear is one call, and a no-op stub is provided when
CONFIG_NET_EGRESS is disabled. skb->nf_skip_egress is compiled under
CONFIG_NET_EGRESS rather than CONFIG_NETFILTER_SKIP_EGRESS, so
skb_at_tc_egress() is valid whenever the egress path is built.
A local user in a network namespace can redirect a packet from a device
with more TX queues to one with fewer after setting a mapping valid only
on the larger device. That reaches these reads and, under KASAN, faults
with "slab-out-of-bounds in taprio_enqueue".
Conditions to recreate the bug: the report's own trigger is a local user
with CAP_NET_ADMIN in a network namespace, so no eBPF program is needed.
With CONFIG_NET_SCH_TAPRIO=y, CONFIG_NET_ACT_SKBEDIT=y,
CONFIG_NET_ACT_MIRRED=y, CONFIG_NET_CLS_MATCHALL=y,
CONFIG_NET_SCH_PRIO=y and KASAN enabled, create qa (3 queues), qb
(2 queues) and qc (1 queue) as dummy devices; put a taprio root on qb
(num_tc 1, queues 2@0) and clsact on all three; then add an egress
matchall filter on every device. On qa: "action skbedit queue_mapping 2
pipe action mirred egress redirect dev qb". On qb: "action mirred egress
mirror dev qc". On qc: "action skbedit queue_mapping 0 pipe". Send one
packet out qa. qc's skbedit sets the flag while qb's outer xmit is in
flight; without the fix qb consumes it and reads its two-entry taprio
child array with the forwarded packet's stale mapping. A qc whose
skb
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: mtk_eth_soc: allocate dummy netdev sooner
The RX rings and the shared NAPI are carried by an internal "dummy" netdev
(eth->dummy_dev). mtk_probe() creates that dummy device, and adds the
shared tx/rx NAPI to it, only after the MAC netdevs have been registered.
That order has been there since the MT7623 support was added and leaves a
window in which the netdevs are visible to the network core before the
shared NAPI and the dummy device exist.
If anything brings the first netdev up during that window (e.g. netifd
opening the WAN link the instant the interface is registered), the
first-open path runs without them. On NETSYS v2 and later SoCs
mtk_rx_alloc() -> __xdp_rxq_info_reg() then dereferences eth->dummy_dev ==
NULL:
WARNING: CPU: ... Missing net_device from driver
in net/core/xdp.c and mtk_open() fails with -ENODEV. On NETSYS v1 SoCs
(MT7621/MT7622/MT7623/MT7629) there is no page pool, so the same open
instead calls napi_enable() on a napi_struct that netif_napi_add() has not
initialised yet and dereferences a NULL napi->dev.
Allocate the dummy netdev and add the shared tx/rx NAPI to it before the
register_netdev() loop. Both the dummy-allocation failure and a
register_netdev() failure now unwind through mtk_unreg_dev(), which
unregisters the net_device notifiers and the netdevs registered so far,
stopping a concurrently-opened netdev (ndo_stop) and its NAPI before the
dummy carrier is freed.
A netdev that opened during the window can also have queued the
frame-engine reset worker (via the tx watchdog or phylink), so the probe
error path now cancels eth->pending_work before freeing the shared state,
as mtk_cleanup() already does on remove. |
| In the Linux kernel, the following vulnerability has been resolved:
net: sparx5: skip ptp deinit if init was skipped
sparx5_ptp_init() returns early on the base lan969x variants
because they do not have the SPX5_FEATURE_PTP flag. It also returns early
when no "ptp" interrupt is described. Unbinding the driver then causes a
NULL pointer dereference when cleaning up uninitialized tx_skbs queues:
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000008
Call trace:
skb_queue_purge_reason+0x68/0x120 (P)
sparx5_ptp_deinit+0x64/0xc0
mchp_sparx5_remove+0x38/0x70
platform_remove+0x20/0x30
device_remove+0x4c/0x80
Before per-port tx_skbs were added, a NULL dereference would have happened
when calling ptp_clock_unregister() on the never-registered PTP clocks.
Fix by returning early in sparx5_ptp_deinit() if PTP is not used. |
| In the Linux kernel, the following vulnerability has been resolved:
ipvs: filter some flags received in the backup server
While the IPVS SYNC protocol is not secure by design
we can still protect the backup server from messages that
can wreak havoc.
This commit addresses problems from received connection flags
or their combinations. We now drop messages as follows:
1. the NO_CPORT+TEMPLATE combination allows lookups for normal
connections to hit template which can break in many ways.
While the master does not sync connections with NO_CPORT flag,
i.e. before they are established, we still accept NO_CPORT
without TEMPLATE.
2. ONE_PACKET: it is not sent by master, so we do not
expect it in backup. Before now it was ignored by
IP_VS_CONN_F_BACKUP_MASK for protocol v1 while protocol
v0 created connections that are not hashed and dropped
immediately. Better to apply the IP_VS_CONN_F_BACKUP_MASK
also to the flags from v0 messages for consistency with v1. |
| In the Linux kernel, the following vulnerability has been resolved:
netfilter: bpf: reject invalid NAT manipulation types
As bpf_ct_set_nat_info() is not validating the NAT manipulation type a
wrong value can be passed directly to nf_nat_setup_info(). This triggers
the WARN_ON() at nf_nat_setup_info() and if panic_on_warn isn't set,
then IPS_SRC_NAT_DONE is set without adding nat_bysource and conntrack
cleanup tries to unlink an uninitialized hlist node.
Fix this by checking that NAT manipulation type is correct before
calling nf_nat_setup_info(). In addition, if the WARN_ON is hit, return
NF_DROP instead of continuing with the processing to avoid similar
situations in the future. |
| In the Linux kernel, the following vulnerability has been resolved:
netfilter: flowtable: generalize pending status bit
Rename NF_FLOW_HW_PENDING to NF_FLOW_PENDING and use it to inhibit the
flowtable GC worker until pending hw offload work has been completed.
Apparently, nf_flow_offload_stats() can schedule work to retrieve stats
while the flow is being removed by GC.
And this bit can also be used in a follow up patch to disable GC until
the flow has been fully added in both directions.
Revert the reordering done in commit d644b23afe1e ("netfilter:
flowtable: publish HW_DEAD after worker is done") to prevent a race
between GC and hw offload handler. |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Fix AF_XDP TX timestamp teardown NULL dereference
During XSK TX queue teardown, outstanding descriptors are completed
without a CQE. If one requested a TX timestamp, the completion path
passes that NULL CQE to mlx5e_xsk_fill_timestamp(), which dereferences
it.
Return zero when no CQE is available, indicating that teardown did not
produce a TX timestamp. |
| In the Linux kernel, the following vulnerability has been resolved:
perf: Fix race between perf_event_exit_task() and perf_pending_task()
A race condition exists between perf_event_exit_task() and
perf_pending_task() during begin_new_exec().
During begin_new_exec(), perf_event_exit_task() may be called, and the
PF_EXITING flag is not set on task. So perf_sigtrap() continues to execute
and triggers WARN_ON_ONCE(event->ctx->task != current).
Since both task exit and exec paths can call perf_event_exit_task() which
sets ctx->task to TASK_TOMBSTONE, fix this by explicitly checking if
event->ctx->task equals TASK_TOMBSTONE and dropping the redundant
PF_EXITING check. |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix objects stuck in free_by_rcu_ttrace
do_call_rcu_ttrace() returns early when call_rcu_ttrace_in_progress is set
and leaves the objects in free_by_rcu_ttrace. __free_rcu() frees
waiting_for_gp_ttrace only and clears the flag. Hence the objects that
free_bulk() or __free_by_rcu() added while RCU tasks trace GP was in flight
stay in free_by_rcu_ttrace until free_bulk() or alloc_bulk() is called for
the same bpf_mem_cache again, which may never happen. The number of such
objects is not bounded.
Turn call_rcu_ttrace_in_progress into three states:
0 - idle
1 - __free_rcu() is queued
2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since
do_call_rcu_ttrace() sets 2. __free_rcu() does cmpxchg(1 -> 0) and starts
the next GP when it fails. It cannot clear the flag first and check
free_by_rcu_ttrace later, since bpf_mem_alloc_destroy() frees bpf_mem_cache
without waiting for RCU callbacks when the flag is zero.
Now __free_rcu() queues itself, so the one that didn't see 'draining' may
do call_rcu_tasks_trace() after rcu_barrier_tasks_trace() in
free_mem_alloc(). Queue it under rcu_read_lock() and do synchronize_rcu()
before the barriers. Calling rcu_barrier_tasks_trace() twice works too, but
creating and destroying hash maps in a loop on many cpus slows down to one
free_mem_alloc() per GP and kworkers pile up. |
| In the Linux kernel, the following vulnerability has been resolved:
futex: Fix private hash use-after-free on resize
poll_state_synchronize_rcu(mm->futex.phash.batches) is used by
futex_ref_drop() to check that a grace period has passed since the
current hash was published. This relies on batches referencing a grace
period which started after the hash pointer was assigned.
__futex_pivot_hash() sets mmph->batches before it replaces mmph->hash:
scoped_guard(rcu) {
mmph->batches = get_state_synchronize_rcu();
rcu_assign_pointer(mmph->hash, new);
}
The scoped_guard(rcu) doesn't stop new grace periods from starting, and
if one starts between those two assignments, futex_ref_drop() can move
forward while a reader still holds a pointer to the old hash.
Fix things by setting mmph->batches after assigning mmph->hash. The
scoped_guard(rcu) isn't needed, so let's drop that as well. |
