{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63883", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.018Z", "datePublished": "2026-07-19T14:54:56.356Z", "dateUpdated": "2026-07-20T13:41:09.305Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-07-20T13:41:09.305Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ\n\nWhen uart_flush_buffer() runs before the DMA completion IRQ is delivered,\nthe following race can occur (all steps serialized by uart_port_lock):\n\n 1. DMA starts: tx_remaining = N, kfifo contains N bytes\n 2. DMA completes in hardware; IRQ is pending but not yet delivered\n 3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(),\n making kfifo_len() = 0 while tx_remaining remains N\n 4. uart_flush_buffer() releases the port lock\n 5. DMA IRQ fires; handle_tx_dma() acquires the port lock and calls\n uart_xmit_advance(uport, tx_remaining) on an empty kfifo\n\nuart_xmit_advance() increments kfifo->out by tx_remaining. Since\nkfifo_reset() already set both in and out to 0, out wraps past in,\ncausing kfifo_len() to return UART_XMIT_SIZE - tx_remaining. The next\nstart_tx_dma() call then submits a DMA transfer of stale buffer data.\n\nFix this by snapshotting kfifo_len() at the start of handle_tx_dma()\nand skipping uart_xmit_advance() when fifo_len < tx_remaining, which\nindicates the kfifo was reset by a preceding flush."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L", "baseScore": 7.3, "baseSeverity": "HIGH"}}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/tty/serial/qcom_geni_serial.c"], "versions": [{"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "c91ea13375f70f6271a0183445e34e83b8f4d8f7", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "b1159dce10b38eb795e4c96cdc4d34b83cec81c5", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "654f45a8569f3cd6ff20bd724a18e0cce65893ba", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46", "status": "affected", "versionType": "git"}, {"version": "2aaa43c7077833301c237684cd7bc9ae5e3dec95", "lessThan": "452d6fa37ae9b021f4f6d397dbae077f7296f6f4", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/tty/serial/qcom_geni_serial.c"], "versions": [{"version": "6.3", "status": "affected"}, {"version": "0", "lessThan": "6.3", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1", "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:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.6.143"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.12.93"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.18.35"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "7.0.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "7.1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/c91ea13375f70f6271a0183445e34e83b8f4d8f7"}, {"url": "https://git.kernel.org/stable/c/b1159dce10b38eb795e4c96cdc4d34b83cec81c5"}, {"url": "https://git.kernel.org/stable/c/654f45a8569f3cd6ff20bd724a18e0cce65893ba"}, {"url": "https://git.kernel.org/stable/c/0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46"}, {"url": "https://git.kernel.org/stable/c/452d6fa37ae9b021f4f6d397dbae077f7296f6f4"}], "title": "serial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ", "x_generator": {"engine": "bippy-1.2.0"}}}}

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