{"api_version":"1","generated_at":"2026-07-24T20:12:58+00:00","cve":"CVE-2026-63883","urls":{"html":"https://cve.report/CVE-2026-63883","api":"https://cve.report/api/cve/CVE-2026-63883.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-63883","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63883"},"summary":{"title":"serial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:05","updated_at":"2026-07-20 15:16:53"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.3","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"LOW"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.3","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L","data":{"baseScore":7.3,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/452d6fa37ae9b021f4f6d397dbae077f7296f6f4","name":"https://git.kernel.org/stable/c/452d6fa37ae9b021f4f6d397dbae077f7296f6f4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b1159dce10b38eb795e4c96cdc4d34b83cec81c5","name":"https://git.kernel.org/stable/c/b1159dce10b38eb795e4c96cdc4d34b83cec81c5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/654f45a8569f3cd6ff20bd724a18e0cce65893ba","name":"https://git.kernel.org/stable/c/654f45a8569f3cd6ff20bd724a18e0cce65893ba","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46","name":"https://git.kernel.org/stable/c/0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c91ea13375f70f6271a0183445e34e83b8f4d8f7","name":"https://git.kernel.org/stable/c/c91ea13375f70f6271a0183445e34e83b8f4d8f7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63883","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63883","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2aaa43c7077833301c237684cd7bc9ae5e3dec95 c91ea13375f70f6271a0183445e34e83b8f4d8f7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2aaa43c7077833301c237684cd7bc9ae5e3dec95 b1159dce10b38eb795e4c96cdc4d34b83cec81c5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2aaa43c7077833301c237684cd7bc9ae5e3dec95 654f45a8569f3cd6ff20bd724a18e0cce65893ba git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2aaa43c7077833301c237684cd7bc9ae5e3dec95 0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2aaa43c7077833301c237684cd7bc9ae5e3dec95 452d6fa37ae9b021f4f6d397dbae077f7296f6f4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.3","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.3 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.143 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.93 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.35 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.12 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"63883","cve":"CVE-2026-63883","epss":"0.002000000","percentile":"0.100190000","score_date":"2026-07-20","updated_at":"2026-07-21 00:13:14"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/tty/serial/qcom_geni_serial.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"c91ea13375f70f6271a0183445e34e83b8f4d8f7","status":"affected","version":"2aaa43c7077833301c237684cd7bc9ae5e3dec95","versionType":"git"},{"lessThan":"b1159dce10b38eb795e4c96cdc4d34b83cec81c5","status":"affected","version":"2aaa43c7077833301c237684cd7bc9ae5e3dec95","versionType":"git"},{"lessThan":"654f45a8569f3cd6ff20bd724a18e0cce65893ba","status":"affected","version":"2aaa43c7077833301c237684cd7bc9ae5e3dec95","versionType":"git"},{"lessThan":"0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46","status":"affected","version":"2aaa43c7077833301c237684cd7bc9ae5e3dec95","versionType":"git"},{"lessThan":"452d6fa37ae9b021f4f6d397dbae077f7296f6f4","status":"affected","version":"2aaa43c7077833301c237684cd7bc9ae5e3dec95","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/tty/serial/qcom_geni_serial.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.3"},{"lessThan":"6.3","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.143","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.93","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.35","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.12","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.143","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.93","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.35","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.12","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"6.3","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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":{"baseScore":7.3,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-07-20T13:41:09.305Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-63883","datePublished":"2026-07-19T14:54:56.356Z","dateReserved":"2026-07-19T07:54:57.018Z","dateUpdated":"2026-07-20T13:41:09.305Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:05","lastModifiedDate":"2026-07-20 15:16:53","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"LOW"},"exploitabilityScore":1.8,"impactScore":5.5}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"63883","Ordinal":"1","Title":"serial: qcom_geni: fix kfifo underflow when flush precedes DMA c","CVE":"CVE-2026-63883","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"63883","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"serial: qcom_geni: fix kfifo underflow when flush precedes DMA c"}]}}}