{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89996", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.780Z", "datePublished": "2026-09-16T10:33:08.620Z", "dateUpdated": "2026-10-21T12:49:22.023Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:49:22.023Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndma-buf: dma-heap: don't publish fd before copy_to_user() succeeds\n\nDMA_HEAP_IOCTL_ALLOC allocates a dma-buf and installs an fd into the\ncaller's fd table via dma_buf_fd() -> fd_install() before\ndma_heap_ioctl() copies the result back to userspace. If the trailing\ncopy_to_user() fails, userspace never learns the fd number, but the\nfd (and the underlying dma-buf reference) are already visible to\nother threads in the same process and are leaked for the lifetime of\nthe process.\n\nThe obvious \"close it on the failure path\" fix is unsafe: once\nfd_install() has run, another thread can already dup() the fd, send\nit via SCM_RIGHTS, or close() it and let its number be reused, so a\nsubsequent close_fd() from the ioctl path can operate on an unrelated\nfile. This was pointed out by Christian König on v1 [1].\n\nRestructure the allocation path so that fd_install() is the last,\nunfailable step of a successful ioctl:\n\n 1. heap->ops->allocate() creates the dma_buf.\n 2. get_unused_fd_flags() reserves an fd number in the caller's\n fd table without publishing it, so\n no other thread can observe it.\n 3. copy_to_user() delivers the fd number to userspace;\n on failure the fd is returned with\n put_unused_fd() and the dma_buf\n reference is dropped with\n dma_buf_put(), leaving no user-\n visible state behind.\n 4. dma_buf_fd_install() publishes the fd and emits the\n trace_dma_buf_fd tracepoint -- from\n here on the ioctl cannot fail.\n\nA new dma_buf_fd_install() helper is introduced in dma-buf.c to wrap\nfd_install() together with the DMA_BUF_TRACE() call, preserving the\nexport tracing that dma_buf_fd() provides. dma_heap_ioctl_allocate()\nis refactored to return the struct dma_buf * directly (returning\nERR_PTR on failure) so the caller holds the dmabuf reference across\nsteps 3 and 4.\n\nThe failure at step 3 is easily reachable from userspace: pass a\nstruct dma_heap_allocation_data that lives in a page whose protection\nis flipped to PROT_READ between copy_from_user() and copy_to_user()\n(e.g. via mprotect()). Before this change each such ioctl leaks one\ndmabuf fd; after it, the fd table is unchanged on failure and only\n/dev/dma_heap/ remains open.\n\nNo UAPI or heap-driver interface change.\n\n[1] https://lore.kernel.org/dri-devel/175e98de-f414-47d7-81c1-c0fe0a8f7f62@amd.com/" } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/dma-buf/dma-buf.c", "drivers/dma-buf/dma-heap.c", "include/linux/dma-buf.h" ], "versions": [ { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "lessThan": "ad61defb3e66ac0c598ad6f39b57f15784543d46", "status": "affected", "versionType": "git" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "lessThan": "1bf6083a41f810d760c4dcd1b80c5194a92575aa", "status": "affected", "versionType": "git" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "lessThan": "69d57dbadb27ffd5eef34fd184bab145500cdabc", "status": "affected", "versionType": "git" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "lessThan": "0d4a5d218055db29b50cc07d3d73d27007c2a391", "status": "affected", "versionType": "git" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "lessThan": "30d0aff2c65a277135cfd8ea28fa1ee75e0ea4e0", "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/dma-buf/dma-buf.c", "drivers/dma-buf/dma-heap.c", "include/linux/dma-buf.h" ], "versions": [ { "version": "5.6", "status": "affected" }, { "version": "0", "lessThan": "5.6", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.5", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "5.6", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "7.2.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ad61defb3e66ac0c598ad6f39b57f15784543d46" }, { "url": "https://git.kernel.org/stable/c/1bf6083a41f810d760c4dcd1b80c5194a92575aa" }, { "url": "https://git.kernel.org/stable/c/69d57dbadb27ffd5eef34fd184bab145500cdabc" }, { "url": "https://git.kernel.org/stable/c/0d4a5d218055db29b50cc07d3d73d27007c2a391" }, { "url": "https://git.kernel.org/stable/c/30d0aff2c65a277135cfd8ea28fa1ee75e0ea4e0" } ], "title": "dma-buf: dma-heap: don't publish fd before copy_to_user() succeeds", "x_generator": { "engine": "bippy-1.2.0" } } } }