{"id":"CVE-2025-21734","state":"PUBLISHED","title":"misc: fastrpc: Fix copy buffer page size","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: fastrpc: Fix copy buffer page size\n\nFor non-registered buffer, fastrpc driver copies the buffer and\npass it to the remote subsystem. There is a problem with current\nimplementation of page size calculation which is not considering\nthe offset in the calculation. This might lead to passing of\nimproper and out-of-bounds page size which could result in\nmemory issue. Calculate page start and page end using the offset\nadjusted address instead of absolute address.","publishedAt":"2025-02-27T02:12:11.663Z","updatedAt":"2026-08-05T11:54:03.438Z","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":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"c56ba3ea8e3c9a69a992aad18f7a65e43e51d623","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"c0464bad0e85fcd5d47e4297d1e410097c979e55","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"24a79c6bc8de763f7c50f4f84f8b0c183bc25a51","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"c3f7161123fcbdc64e90119ccce292d8b66281c4","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"e966eae72762ecfdbdb82627e2cda48845b9dd66","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/misc/fastrpc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.2","versionType":"semver"},{"version":"6.1.129","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.78","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.14","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.3","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/misc/fastrpc.c"]}],"references":["https://git.kernel.org/stable/c/c56ba3ea8e3c9a69a992aad18f7a65e43e51d623","https://git.kernel.org/stable/c/c0464bad0e85fcd5d47e4297d1e410097c979e55","https://git.kernel.org/stable/c/24a79c6bc8de763f7c50f4f84f8b0c183bc25a51","https://git.kernel.org/stable/c/c3f7161123fcbdc64e90119ccce292d8b66281c4","https://git.kernel.org/stable/c/e966eae72762ecfdbdb82627e2cda48845b9dd66","https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21734.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21734","state":"PUBLISHED","datePublished":"2025-02-27T02:12:11.663Z","dateUpdated":"2026-08-05T11:54:03.438Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.756Z"},"containers":{"cna":{"title":"misc: fastrpc: Fix copy buffer page size","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: fastrpc: Fix copy buffer page size\n\nFor non-registered buffer, fastrpc driver copies the buffer and\npass it to the remote subsystem. There is a problem with current\nimplementation of page size calculation which is not considering\nthe offset in the calculation. This might lead to passing of\nimproper and out-of-bounds page size which could result in\nmemory issue. Calculate page start and page end using the offset\nadjusted address instead of absolute address."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"c56ba3ea8e3c9a69a992aad18f7a65e43e51d623","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"c0464bad0e85fcd5d47e4297d1e410097c979e55","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"24a79c6bc8de763f7c50f4f84f8b0c183bc25a51","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"c3f7161123fcbdc64e90119ccce292d8b66281c4","versionType":"git"},{"version":"02b45b47fbe84e23699bb6bdc74d4c2780e282b4","status":"affected","lessThan":"e966eae72762ecfdbdb82627e2cda48845b9dd66","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/misc/fastrpc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.2","versionType":"semver"},{"version":"6.1.129","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.78","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.14","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.3","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/misc/fastrpc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c56ba3ea8e3c9a69a992aad18f7a65e43e51d623"},{"url":"https://git.kernel.org/stable/c/c0464bad0e85fcd5d47e4297d1e410097c979e55"},{"url":"https://git.kernel.org/stable/c/24a79c6bc8de763f7c50f4f84f8b0c183bc25a51"},{"url":"https://git.kernel.org/stable/c/c3f7161123fcbdc64e90119ccce292d8b66281c4"},{"url":"https://git.kernel.org/stable/c/e966eae72762ecfdbdb82627e2cda48845b9dd66"}],"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 vulnerable code is reached only through the FASTRPC_IOCTL_INVOKE ioctl on the /dev/fastrpc-* character device, requiring local access to the system. There is no network-facing path into fastrpc_get_args().\nAC:L - The attacker fully and deterministically controls every input that produces the miscalculation — the overlap offset (via user-supplied overlapping args[i].ptr/length ranges), the in-page alignment of `args` (via nscalars-derived metalen and preceding buffer lengths), and the buffer length — so the wrong page count can be produced reliably on the first attempt with no race or unpredictable state.\nPR:L - No capability check exists anywhere on the ioctl path; an unprivileged process only needs to open the fastrpc device node, and the driver explicitly registers a non-secure node for untrusted applications to offload to unsigned PDs (`is_session_rejected()`), which is exactly how untrusted Android apps use CDSP.\nUI:N - The attacker performs the entire sequence (open, init, invoke) itself from its own process; no victim action of any kind is needed.\nS:U - The vulnerable component and the impacted memory are both the host Linux kernel, so the exploit stays within a single security authority — this is standard local kernel memory corruption/privilege escalation rather than a VM or hypervisor boundary escape.\nC:H - An over-computed pages[i].size hands the DSP a physical page descriptor covering kernel memory beyond the coherent copy buffer, and on the unsigned-PD path the attacker controls the DSP-side code that reads that mapping and returns the contents, yielding disclosure of adjacent kernel memory.\nI:H - The same out-of-bounds page grant is read/write from the coprocessor's side, so attacker-controlled DSP code can write into kernel memory adjacent to the DMA-coherent allocation, giving a corruption primitive usable for privilege escalation.\nA:H - The mismatched page list either lets the DSP corrupt kernel memory outside the buffer or, in the under-sized direction, causes SMMU context faults and DSP subsystem crashes/restarts, and the ioctl can be repeated at will by any process holding the device fd."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:54:03.438Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.1.129"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.6.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.12.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.13.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2","versionEndExcluding":"6.14"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T19:36:37.586Z"}}]}}}