{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-89996", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-89996", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-09-16T10:33:08.620Z", "updatedAt": "2026-10-21T12:49:22.023Z", "importedAt": "2026-10-24T01:58:35.090Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "dma-buf: dma-heap: don't publish fd before copy_to_user() succeeds", "summary": "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": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "status": "affected", "versionType": "git", "lessThan": "ad61defb3e66ac0c598ad6f39b57f15784543d46" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "status": "affected", "versionType": "git", "lessThan": "1bf6083a41f810d760c4dcd1b80c5194a92575aa" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "status": "affected", "versionType": "git", "lessThan": "69d57dbadb27ffd5eef34fd184bab145500cdabc" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "status": "affected", "versionType": "git", "lessThan": "0d4a5d218055db29b50cc07d3d73d27007c2a391" }, { "version": "c02a81fba74fe3488ad6b08bfb5a1329005418f8", "status": "affected", "versionType": "git", "lessThan": "30d0aff2c65a277135cfd8ea28fa1ee75e0ea4e0" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "5.6", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "5.6" }, { "version": "6.6.160", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.112", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.52", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.2.5", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.2.*" }, { "version": "7.3", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }