{"api_version":"1","generated_at":"2026-07-22T13:17:54+00:00","cve":"CVE-2026-63929","urls":{"html":"https://cve.report/CVE-2026-63929","api":"https://cve.report/api/cve/CVE-2026-63929.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-63929","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63929"},"summary":{"title":"iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()\n\niio_buffer_enqueue_dmabuf() allocates a struct iio_dma_fence (104 bytes,\nkmalloc-128) via kmalloc_obj()+dma_fence_init(), which sets the initial\nkref to 1.  It then calls dma_resv_add_fence() which takes a second\nreference (kref=2), and stores a raw pointer in block->fence.\n\nOn the success path the function returns without calling dma_fence_put()\nto release the initial reference, so every buffer enqueue permanently\nleaks one kmalloc-128 allocation.\n\nThe iio_buffer_cleanup() work item only releases the temporary reference\ntaken during completion signalling by iio_buffer_signal_dmabuf_done();\nthe initial reference from dma_fence_init() is never released.\n\nWith four iio_rwdev instances at 240kHz and 512 samples per buffer,\nthis produces ~1875 kmalloc-128 allocations per second matching the\nobserved slab growth exactly. A test with ftrace confirmed that the\ndma_fence_destroy event was never triggered.\n\nFix by calling dma_fence_put() after dma_resv_add_fence(), transferring\nownership of the fence to the DMA reservation object. The DMA fence then\ngets properly discarded after being signalled.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:11","updated_at":"2026-07-19 16:17:11"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/96cdeaba6a008503455b78a9641c05c2a886a7ec","name":"https://git.kernel.org/stable/c/96cdeaba6a008503455b78a9641c05c2a886a7ec","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a093999355084bdbfe6e97f1dd232e58a1525f0b","name":"https://git.kernel.org/stable/c/a093999355084bdbfe6e97f1dd232e58a1525f0b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3412a95afaa5d3262008dfc34f3c7be33d8151dc","name":"https://git.kernel.org/stable/c/3412a95afaa5d3262008dfc34f3c7be33d8151dc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9678aeed8b77d495a417dd057d479f3733094019","name":"https://git.kernel.org/stable/c/9678aeed8b77d495a417dd057d479f3733094019","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63929","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63929","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f 9678aeed8b77d495a417dd057d479f3733094019 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f 3412a95afaa5d3262008dfc34f3c7be33d8151dc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f 96cdeaba6a008503455b78a9641c05c2a886a7ec git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f a093999355084bdbfe6e97f1dd232e58a1525f0b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.11","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.11 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":"63929","cve":"CVE-2026-63929","epss":"0.002000000","percentile":"0.100170000","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/iio/industrialio-buffer.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"9678aeed8b77d495a417dd057d479f3733094019","status":"affected","version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","versionType":"git"},{"lessThan":"3412a95afaa5d3262008dfc34f3c7be33d8151dc","status":"affected","version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","versionType":"git"},{"lessThan":"96cdeaba6a008503455b78a9641c05c2a886a7ec","status":"affected","version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","versionType":"git"},{"lessThan":"a093999355084bdbfe6e97f1dd232e58a1525f0b","status":"affected","version":"3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/iio/industrialio-buffer.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.11"},{"lessThan":"6.11","status":"unaffected","version":"0","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":"6.12.93","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.35","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.12","versionStartIncluding":"6.11","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"6.11","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()\n\niio_buffer_enqueue_dmabuf() allocates a struct iio_dma_fence (104 bytes,\nkmalloc-128) via kmalloc_obj()+dma_fence_init(), which sets the initial\nkref to 1.  It then calls dma_resv_add_fence() which takes a second\nreference (kref=2), and stores a raw pointer in block->fence.\n\nOn the success path the function returns without calling dma_fence_put()\nto release the initial reference, so every buffer enqueue permanently\nleaks one kmalloc-128 allocation.\n\nThe iio_buffer_cleanup() work item only releases the temporary reference\ntaken during completion signalling by iio_buffer_signal_dmabuf_done();\nthe initial reference from dma_fence_init() is never released.\n\nWith four iio_rwdev instances at 240kHz and 512 samples per buffer,\nthis produces ~1875 kmalloc-128 allocations per second matching the\nobserved slab growth exactly. A test with ftrace confirmed that the\ndma_fence_destroy event was never triggered.\n\nFix by calling dma_fence_put() after dma_resv_add_fence(), transferring\nownership of the fence to the DMA reservation object. The DMA fence then\ngets properly discarded after being signalled."}],"providerMetadata":{"dateUpdated":"2026-07-19T14:55:29.309Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/9678aeed8b77d495a417dd057d479f3733094019"},{"url":"https://git.kernel.org/stable/c/3412a95afaa5d3262008dfc34f3c7be33d8151dc"},{"url":"https://git.kernel.org/stable/c/96cdeaba6a008503455b78a9641c05c2a886a7ec"},{"url":"https://git.kernel.org/stable/c/a093999355084bdbfe6e97f1dd232e58a1525f0b"}],"title":"iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-63929","datePublished":"2026-07-19T14:55:29.309Z","dateReserved":"2026-07-19T07:54:57.021Z","dateUpdated":"2026-07-19T14:55:29.309Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:11","lastModifiedDate":"2026-07-19 16:17:11","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"63929","Ordinal":"1","Title":"iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()","CVE":"CVE-2026-63929","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"63929","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()\n\niio_buffer_enqueue_dmabuf() allocates a struct iio_dma_fence (104 bytes,\nkmalloc-128) via kmalloc_obj()+dma_fence_init(), which sets the initial\nkref to 1.  It then calls dma_resv_add_fence() which takes a second\nreference (kref=2), and stores a raw pointer in block->fence.\n\nOn the success path the function returns without calling dma_fence_put()\nto release the initial reference, so every buffer enqueue permanently\nleaks one kmalloc-128 allocation.\n\nThe iio_buffer_cleanup() work item only releases the temporary reference\ntaken during completion signalling by iio_buffer_signal_dmabuf_done();\nthe initial reference from dma_fence_init() is never released.\n\nWith four iio_rwdev instances at 240kHz and 512 samples per buffer,\nthis produces ~1875 kmalloc-128 allocations per second matching the\nobserved slab growth exactly. A test with ftrace confirmed that the\ndma_fence_destroy event was never triggered.\n\nFix by calling dma_fence_put() after dma_resv_add_fence(), transferring\nownership of the fence to the DMA reservation object. The DMA fence then\ngets properly discarded after being signalled.","Type":"Description","Title":"iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()"}]}}}