{"id":"CVE-2026-63910","state":"PUBLISHED","title":"dma-buf: fix UAF in dma_buf_fd() tracepoint","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndma-buf: fix UAF in dma_buf_fd() tracepoint\n\nOnce FD_ADD() returns, the fd is live in the file descriptor table\nand a thread sharing that table can close() it before DMA_BUF_TRACE()\nruns. The close drops the last reference, __fput() frees the dma_buf,\nand the tracepoint then dereferences dmabuf to take dmabuf->name_lock\n-- slab-use-after-free.\n\nSplit FD_ADD() back into get_unused_fd_flags() + fd_install() and\nemit the tracepoint between them. While the fdtable slot is reserved\nwith a NULL file pointer, a racing close() returns -EBADF without\nentering __fput(), so the dma_buf stays alive across the trace. Same\napproach as commit 2d76319c4cbb (\"dma-buf: fix UAF in dma_buf_put()\ntracepoint\").\n\nThis undoes the FD_ADD() conversion done in commit 34dfce523c90\n(\"dma: convert dma_buf_fd() to FD_ADD()\"); FD_ADD() has no place to\nhook the tracepoint safely.","publishedAt":"2026-07-19T14:55:15.770Z","updatedAt":"2026-08-05T12:37:04.026Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"281a226314238e8adb08d11b765347687ffb38b9","status":"affected","lessThan":"b569f86e2f8dbf6f11d31d3de794d22e18098b23","versionType":"git"},{"version":"281a226314238e8adb08d11b765347687ffb38b9","status":"affected","lessThan":"ead6680f354f83966c796fc7f9463a3171789616","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/dma-buf/dma-buf.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.0","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/dma-buf/dma-buf.c"]}],"references":["https://git.kernel.org/stable/c/b569f86e2f8dbf6f11d31d3de794d22e18098b23","https://git.kernel.org/stable/c/ead6680f354f83966c796fc7f9463a3171789616"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63910.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63910","state":"PUBLISHED","datePublished":"2026-07-19T14:55:15.770Z","dateUpdated":"2026-08-05T12:37:04.026Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.020Z"},"containers":{"cna":{"title":"dma-buf: fix UAF in dma_buf_fd() tracepoint","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndma-buf: fix UAF in dma_buf_fd() tracepoint\n\nOnce FD_ADD() returns, the fd is live in the file descriptor table\nand a thread sharing that table can close() it before DMA_BUF_TRACE()\nruns. The close drops the last reference, __fput() frees the dma_buf,\nand the tracepoint then dereferences dmabuf to take dmabuf->name_lock\n-- slab-use-after-free.\n\nSplit FD_ADD() back into get_unused_fd_flags() + fd_install() and\nemit the tracepoint between them. While the fdtable slot is reserved\nwith a NULL file pointer, a racing close() returns -EBADF without\nentering __fput(), so the dma_buf stays alive across the trace. Same\napproach as commit 2d76319c4cbb (\"dma-buf: fix UAF in dma_buf_put()\ntracepoint\").\n\nThis undoes the FD_ADD() conversion done in commit 34dfce523c90\n(\"dma: convert dma_buf_fd() to FD_ADD()\"); FD_ADD() has no place to\nhook the tracepoint safely."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"281a226314238e8adb08d11b765347687ffb38b9","status":"affected","lessThan":"b569f86e2f8dbf6f11d31d3de794d22e18098b23","versionType":"git"},{"version":"281a226314238e8adb08d11b765347687ffb38b9","status":"affected","lessThan":"ead6680f354f83966c796fc7f9463a3171789616","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/dma-buf/dma-buf.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.0","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/dma-buf/dma-buf.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b569f86e2f8dbf6f11d31d3de794d22e18098b23"},{"url":"https://git.kernel.org/stable/c/ead6680f354f83966c796fc7f9463a3171789616"}],"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:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The UAF is reached only through local syscalls/ioctls (e.g. UDMABUF_CREATE, DMA_HEAP_IOCTL_ALLOC, DRM/videobuf2 buffer export) that call dma_buf_fd(); there is no network or physical-device entry point.\nAC:L - Exploitation requires a race between dma_buf_fd() and close() on a shared fd table, but the attacker controls both threads and can hammer the window concurrently; syzkaller demonstrated reliable triggering without conditions outside attacker control.\nPR:L - An unprivileged local user with access to dma-buf interfaces (udmabuf, dma_heap, DRM render node, or media devices) can reach dma_buf_fd(); syzbot confirmed unprivileged and user-namespace reachability without real root in the init namespace.\nUI:N - Exploitation is performed entirely by the attacker's own multi-threaded process issuing ioctls and close() calls; no action by a separate victim user is required.\nS:U - Impact is kernel memory corruption and privilege escalation within the same kernel security domain; this is standard local kernel compromise, not a VM escape or IOMMU/DMA boundary bypass.\nC:H - The bug is a slab use-after-free on struct dma_buf; the tracepoint dereferences freed memory (name_lock, exp_name, file fields), enabling controlled reuse of freed kmalloc-1k objects for arbitrary kernel memory disclosure.\nI:H - UAF on a kmalloc-1k kernel object with spinlock interaction provides heap corruption primitives that can be developed into arbitrary kernel writes and local privilege escalation.\nA:H - Winning the race causes a confirmed slab-use-after-free in dma_buf_fd() (KASAN/lockdep fault), which can panic or oops the kernel even when not fully exploited for code execution."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:37:04.026Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}