{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43050", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:55.979Z", "datePublished": "2026-05-01T14:15:44.542Z", "dateUpdated": "2026-05-01T14:15:44.542Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-01T14:15:44.542Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix use-after-free in sock_def_readable()\n\nA race condition exists between lec_atm_close() setting priv->lecd\nto NULL and concurrent access to priv->lecd in send_to_lecd(),\nlec_handle_bridge(), and lec_atm_send(). When the socket is freed\nvia RCU while another thread is still using it, a use-after-free\noccurs in sock_def_readable() when accessing the socket's wait queue.\n\nThe root cause is that lec_atm_close() clears priv->lecd without\nany synchronization, while callers dereference priv->lecd without\nany protection against concurrent teardown.\n\nFix this by converting priv->lecd to an RCU-protected pointer:\n- Mark priv->lecd as __rcu in lec.h\n- Use rcu_assign_pointer() in lec_atm_close() and lecd_attach()\n for safe pointer assignment\n- Use rcu_access_pointer() for NULL checks that do not dereference\n the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and\n lecd_attach()\n- Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(),\n lec_handle_bridge() and lec_atm_send() to safely access lecd\n- Use rcu_assign_pointer() followed by synchronize_rcu() in\n lec_atm_close() to ensure all readers have completed before\n proceeding. This is safe since lec_atm_close() is called from\n vcc_release() which holds lock_sock(), a sleeping lock.\n- Remove the manual sk_receive_queue drain from lec_atm_close()\n since vcc_destroy_socket() already drains it after lec_atm_close()\n returns.\n\nv2: Switch from spinlock + sock_hold/put approach to RCU to properly\n fix the race. The v1 spinlock approach had two issues pointed out\n by Eric Dumazet:\n 1. priv->lecd was still accessed directly after releasing the\n lock instead of using a local copy.\n 2. The spinlock did not prevent packets being queued after\n lec_atm_close() drains sk_receive_queue since timer and\n workqueue paths bypass netif_stop_queue().\n\nNote: Syzbot patch testing was attempted but the test VM terminated\n unexpectedly with \"Connection to localhost closed by remote host\",\n likely due to a QEMU AHCI emulation issue unrelated to this fix.\n Compile testing with \"make W=1 net/atm/lec.o\" passes cleanly."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/atm/lec.c", "net/atm/lec.h"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3e8b25f32f2f35549d03d77da030a24a45bdef5b", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "750a33f417f3d196b86375f8d9f8938bacf130fe", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "317843d5355062020649124eb4a0d7acbcc3f53e", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "b256d055da47258e63f8b40965f276c5f23d229a", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3989740fa4978e1d2d51ecc62be1b01093e104ad", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "abc10f85a3965ac14b9ed7ad3e67b35604a63aa3", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "5fbbb1ff936d7ff9528d929c1549977e8123d8a8", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "922814879542c2e397b0e9641fd36b8202a8e555", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/atm/lec.c", "net/atm/lec.h"], "versions": [{"version": "5.10.253", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.168", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.134", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.81", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.22", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19.12", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.10.253"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.15.203"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.1.168"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.6.134"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.12.81"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.18.22"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.19.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.0"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/3e8b25f32f2f35549d03d77da030a24a45bdef5b"}, {"url": "https://git.kernel.org/stable/c/750a33f417f3d196b86375f8d9f8938bacf130fe"}, {"url": "https://git.kernel.org/stable/c/317843d5355062020649124eb4a0d7acbcc3f53e"}, {"url": "https://git.kernel.org/stable/c/b256d055da47258e63f8b40965f276c5f23d229a"}, {"url": "https://git.kernel.org/stable/c/3989740fa4978e1d2d51ecc62be1b01093e104ad"}, {"url": "https://git.kernel.org/stable/c/abc10f85a3965ac14b9ed7ad3e67b35604a63aa3"}, {"url": "https://git.kernel.org/stable/c/5fbbb1ff936d7ff9528d929c1549977e8123d8a8"}, {"url": "https://git.kernel.org/stable/c/922814879542c2e397b0e9641fd36b8202a8e555"}], "title": "atm: lec: fix use-after-free in sock_def_readable()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix use-after-free in sock_def_readable()\n\nA race condition exists between lec_atm_close() setting priv->lecd\nto NULL and concurrent access to priv->lecd in send_to_lecd(),\nlec_handle_bridge(), and lec_atm_send(). When the socket is freed\nvia RCU while another thread is still using it, a use-after-free\noccurs in sock_def_readable() when accessing the socket's wait queue.\n\nThe root cause is that lec_atm_close() clears priv->lecd without\nany synchronization, while callers dereference priv->lecd without\nany protection against concurrent teardown.\n\nFix this by converting priv->lecd to an RCU-protected pointer:\n- Mark priv->lecd as __rcu in lec.h\n- Use rcu_assign_pointer() in lec_atm_close() and lecd_attach()\n for safe pointer assignment\n- Use rcu_access_pointer() for NULL checks that do not dereference\n the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and\n lecd_attach()\n- Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(),\n lec_handle_bridge() and lec_atm_send() to safely access lecd\n- Use rcu_assign_pointer() followed by synchronize_rcu() in\n lec_atm_close() to ensure all readers have completed before\n proceeding. This is safe since lec_atm_close() is called from\n vcc_release() which holds lock_sock(), a sleeping lock.\n- Remove the manual sk_receive_queue drain from lec_atm_close()\n since vcc_destroy_socket() already drains it after lec_atm_close()\n returns.\n\nv2: Switch from spinlock + sock_hold/put approach to RCU to properly\n fix the race. The v1 spinlock approach had two issues pointed out\n by Eric Dumazet:\n 1. priv->lecd was still accessed directly after releasing the\n lock instead of using a local copy.\n 2. The spinlock did not prevent packets being queued after\n lec_atm_close() drains sk_receive_queue since timer and\n workqueue paths bypass netif_stop_queue().\n\nNote: Syzbot patch testing was attempted but the test VM terminated\n unexpectedly with \"Connection to localhost closed by remote host\",\n likely due to a QEMU AHCI emulation issue unrelated to this fix.\n Compile testing with \"make W=1 net/atm/lec.o\" passes cleanly."}], "id": "CVE-2026-43050", "lastModified": "2026-05-01T15:24:14.893", "metrics": {}, "published": "2026-05-01T15:16:51.403", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/317843d5355062020649124eb4a0d7acbcc3f53e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3989740fa4978e1d2d51ecc62be1b01093e104ad"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3e8b25f32f2f35549d03d77da030a24a45bdef5b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/5fbbb1ff936d7ff9528d929c1549977e8123d8a8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/750a33f417f3d196b86375f8d9f8938bacf130fe"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/922814879542c2e397b0e9641fd36b8202a8e555"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/abc10f85a3965ac14b9ed7ad3e67b35604a63aa3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b256d055da47258e63f8b40965f276c5f23d229a"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

{}

{}