{"id":"CVE-2026-46066","title":"ceph: fix num_ops off-by-one when crypto allocation fails","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix num_ops off-by-one when crypto allocation fails\n\nmove_dirty_folio_in_page_array() may fail if the file is encrypted, the\ndirty folio is not the first in the b…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < f65a96fe2467a9b184c6ae963d95a260a202c98e","Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < 5dd151799d826d3736ae60c2b22cbc9d96a2a613","Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < 6200f41d6fcf2ac7e24866431e381cbc914560e4","Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < ba12c1e578890f6337a415b7dedf476c6d455105","Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842","Linux 6.6"],"published":"2026-05-27","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:41:16.157Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-46066","references":[{"url":"https://git.kernel.org/stable/c/f65a96fe2467a9b184c6ae963d95a260a202c98e"},{"url":"https://git.kernel.org/stable/c/5dd151799d826d3736ae60c2b22cbc9d96a2a613"},{"url":"https://git.kernel.org/stable/c/6200f41d6fcf2ac7e24866431e381cbc914560e4"},{"url":"https://git.kernel.org/stable/c/ba12c1e578890f6337a415b7dedf476c6d455105"},{"url":"https://git.kernel.org/stable/c/a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842"}],"tags":["cve.org"],"epss":0.0016,"epssPercentile":0.04784,"ingestedAt":"2026-10-21T12:48:53.631Z","slug":"CVE-2026-46066","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix num_ops off-by-one when crypto allocation fails\n\nmove_dirty_folio_in_page_array() may fail if the file is encrypted, the\ndirty folio is not the first in the batch, and it fails to allocate a\nbounce buffer to hold the ciphertext. When that happens,\nceph_process_folio_batch() simply redirties the folio and flushes the\ncurrent batch -- it can retry that folio in a future batch.\n\nHowever, if this failed folio is not contiguous with the last folio that\ndid make it into the batch, then ceph_process_folio_batch() has already\nincremented `ceph_wbc->num_ops`; because it doesn't follow through and\nadd the discontiguous folio to the array, ceph_submit_write() -- which\nexpects that `ceph_wbc->num_ops` accurately reflects the number of\ncontiguous ranges (and therefore the required number of \"write extent\"\nops) in the writeback -- will panic the kernel:\n\n    BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops);\n\nThis issue can be reproduced on affected kernels by writing to\nfscrypt-enabled CephFS file(s) with a 4KiB-written/4KiB-skipped/repeat\npattern (total filesize should not matter) and gradually increasing the\nsystem's memory pressure until a bounce buffer allocation fails.\n\nFix this crash by decrementing `ceph_wbc->num_ops` back to the correct\nvalue when move_dirty_folio_in_page_array() fails, but the folio already\nstarted counting a new (i.e. still-empty) extent.\n\nThe defect corrected by this patch has existed since 2022 (see first\n`Fixes:`), but another bug blocked multi-folio encrypted writeback until\nrecently (see second `Fixes:`). The second commit made it into 6.18.16,\n6.19.6, and 7.0-rc1, unmasking the panic in those versions. This patch\ntherefore fixes a regression (panic) introduced by cac190c7674f.\n\n## Affected\n\n- `Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < f65a96fe2467a9b184c6ae963d95a260a202c98e`\n- `Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < 5dd151799d826d3736ae60c2b22cbc9d96a2a613`\n- `Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < 6200f41d6fcf2ac7e24866431e381cbc914560e4`\n- `Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < ba12c1e578890f6337a415b7dedf476c6d455105`\n- `Linux >= d55207717ded95c8f2760a30e93319fa313186e6 < a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842`\n- `Linux 6.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}