{"id":"CVE-2025-21832","state":"PUBLISHED","title":"block: don't revert iter for -EIOCBQUEUED","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nblock: don't revert iter for -EIOCBQUEUED\n\nblkdev_read_iter() has a few odd checks, like gating the position and\ncount adjustment on whether or not the result is bigger-than-or-equal to\nzero (where bigger than makes more sense), and not checking the return\nvalue of blkdev_direct_IO() before doing an iov_iter_revert(). The\nlatter can lead to attempting to revert with a negative value, which\nwhen passed to iov_iter_revert() as an unsigned value will lead to\nthrowing a WARN_ON() because unroll is bigger than MAX_RW_COUNT.\n\nBe sane and don't revert for -EIOCBQUEUED, like what is done in other\nspots.","publishedAt":"2025-03-06T16:22:34.125Z","updatedAt":"2026-10-15T21:51:53.845Z","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":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"6c26619effb1b4cb7d20b4e666ab8f71f6a53ccb","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"84671b0630ccb46ae9f1f99a45c7d63ffcd6a474","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"68f16d3034a06661245ecd22f0d586a8b4e7c473","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"a58f136bad29f9ae721a29d98c042fddbee22f77","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"b13ee668e8280ca5b07f8ce2846b9957a8a10853","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/fops.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.17","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":["block/fops.c"]}],"references":["https://git.kernel.org/stable/c/6c26619effb1b4cb7d20b4e666ab8f71f6a53ccb","https://git.kernel.org/stable/c/84671b0630ccb46ae9f1f99a45c7d63ffcd6a474","https://git.kernel.org/stable/c/68f16d3034a06661245ecd22f0d586a8b4e7c473","https://git.kernel.org/stable/c/a58f136bad29f9ae721a29d98c042fddbee22f77","https://git.kernel.org/stable/c/b13ee668e8280ca5b07f8ce2846b9957a8a10853","https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21832.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21832","state":"PUBLISHED","datePublished":"2025-03-06T16:22:34.125Z","dateUpdated":"2026-10-15T21:51:53.845Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.777Z"},"containers":{"cna":{"title":"block: don't revert iter for -EIOCBQUEUED","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nblock: don't revert iter for -EIOCBQUEUED\n\nblkdev_read_iter() has a few odd checks, like gating the position and\ncount adjustment on whether or not the result is bigger-than-or-equal to\nzero (where bigger than makes more sense), and not checking the return\nvalue of blkdev_direct_IO() before doing an iov_iter_revert(). The\nlatter can lead to attempting to revert with a negative value, which\nwhen passed to iov_iter_revert() as an unsigned value will lead to\nthrowing a WARN_ON() because unroll is bigger than MAX_RW_COUNT.\n\nBe sane and don't revert for -EIOCBQUEUED, like what is done in other\nspots."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"6c26619effb1b4cb7d20b4e666ab8f71f6a53ccb","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"84671b0630ccb46ae9f1f99a45c7d63ffcd6a474","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"68f16d3034a06661245ecd22f0d586a8b4e7c473","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"a58f136bad29f9ae721a29d98c042fddbee22f77","versionType":"git"},{"version":"3e1f941dd9f33776b3df4e30f741fe445ff773f3","status":"affected","lessThan":"b13ee668e8280ca5b07f8ce2846b9957a8a10853","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/fops.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.17","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":["block/fops.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/6c26619effb1b4cb7d20b4e666ab8f71f6a53ccb"},{"url":"https://git.kernel.org/stable/c/84671b0630ccb46ae9f1f99a45c7d63ffcd6a474"},{"url":"https://git.kernel.org/stable/c/68f16d3034a06661245ecd22f0d586a8b4e7c473"},{"url":"https://git.kernel.org/stable/c/a58f136bad29f9ae721a29d98c042fddbee22f77"},{"url":"https://git.kernel.org/stable/c/b13ee668e8280ca5b07f8ce2846b9957a8a10853"}],"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 bug is reached through local syscalls only — io_uring submission (or aio) of an O_DIRECT read against a block device file descriptor. There is no network-facing path into `blkdev_read_iter()`.\nAC:L - The attacker controls both sides of the race: setting `IOSQE_ASYNC` forces io-wq offload so the completion runs in parallel with the still-executing `blkdev_read_iter()`, and choosing a fast backing device (NVMe/brd/null_blk/loop) plus unbounded submission retries makes the window trivially winnable.\nPR:L - Only an unprivileged local account is needed, holding a readable block device node opened with O_DIRECT — commonly available via the disk/cdrom groups, udev uaccess on removable media, containers with device access, and embedded/automotive/IoT images where the application user has raw device access. No CAP_SYS_ADMIN or root is required.\nUI:N - The attacker submits the io_uring read entirely on their own; no victim action, mount, or file open by another user is involved.\nS:U - The freed object, the corruption, and the resulting impact are all within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free — `iov_iter_count()`/`iov_iter_revert()` read the recycled `io_async_rw` and walk backwards out of bounds through a freed or reused bvec/iovec array, and the resulting corrupted iter can be consumed by another in-flight request to DMA arbitrary kernel memory back to the attacker.\nI:H - `iov_iter_revert()` writes `count`, `iov_offset`, `nr_segs`, and the `bvec`/`__iov` pointer into freed/recycled heap memory with an attacker-influenced `unroll`, giving heap-spray-able corruption of a concurrently used iterator that is exploitable for out-of-bounds writes and control-flow hijacking.\nA:H - The reported symptom is a `WARN_ON()` in `iov_iter_revert()` (immediate panic under panic_on_warn), and for the common `ITER_UBUF`/xarray iters the same path hits an unconditional `BUG()`; the underlying use-after-free also crashes the kernel outright under KASAN or on heap corruption."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:54:48.618Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.1.129"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.6.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.12.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.13.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","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":"2025-11-03T21:00:04.401Z"}},{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 TM MFP - GNU/Linux subsystem","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:04:38.526Z"},"x_adpType":"supplier"},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-21832","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:43:12.218426Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T21:51:53.845Z"}}]}}}