{"id":"CVE-2026-74321","title":"btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()\n\nIn the beginning of the loop, we try to obtain a locked delayed ref head,\nif 'locked_ref' is curre…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < c372ca227e16bace86f1df1fa4ae6849e2fcfa28","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < a71143590ce9764dbcb47617647592ff8b4d48bc","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 65770111a2d47c2b15e20b2ba92bb12198f289d4","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 015dc4a1e0c2cba551d4620eba13d26d5081dc34","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < ba9fa2ff5981589bb49094d3358c339b37c47f53","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 9faa6b69ad73f03c7bde53e07d75a28822dc9a1a","Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae","Linux 4.20"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T18:53:22.742693Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:32.917Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74321","references":[{"url":"https://git.kernel.org/stable/c/c372ca227e16bace86f1df1fa4ae6849e2fcfa28"},{"url":"https://git.kernel.org/stable/c/a71143590ce9764dbcb47617647592ff8b4d48bc"},{"url":"https://git.kernel.org/stable/c/65770111a2d47c2b15e20b2ba92bb12198f289d4"},{"url":"https://git.kernel.org/stable/c/015dc4a1e0c2cba551d4620eba13d26d5081dc34"},{"url":"https://git.kernel.org/stable/c/ba9fa2ff5981589bb49094d3358c339b37c47f53"},{"url":"https://git.kernel.org/stable/c/3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1"},{"url":"https://git.kernel.org/stable/c/9faa6b69ad73f03c7bde53e07d75a28822dc9a1a"},{"url":"https://git.kernel.org/stable/c/486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae"}],"tags":["cve.org"],"epss":0.00716,"epssPercentile":0.52838,"ingestedAt":"2026-10-16T19:46:24.379Z","slug":"CVE-2026-74321","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()\n\nIn the beginning of the loop, we try to obtain a locked delayed ref head,\nif 'locked_ref' is currently NULL, by calling btrfs_select_ref_head(),\nwhich can return an error pointer. If the error pointer is -EAGAIN we do\na continue and go back to the beginning of the loop, which will not try\nagain to call btrfs_select_ref_head() since 'locked_ref' is no longer\nNULL but it's ERR_PTR(-EAGAIN), and then we do:\n\n   spin_lock(&locked_ref->lock);\n\nagainst a ERR_PTR(-EAGAIN) value, generating an invalid pointer\ndereference.\n\nFix this by ensuring that 'locked_ref' is set to NULL when\nbtrfs_select_ref_head() returns ERR_PTR(-EAGAIN) and incrementing 'count'\nas well, to prevent infinite looping. We do this by doing a goto to the\nbottom of the loop that already sets 'locked_ref' to NULL and does a\ncond_resched(), with an increment to 'count' right before the goto.\nThese measures were in place before the refactoring in commit 0110a4c43451\n(\"btrfs: refactor __btrfs_run_delayed_refs loop\") but were unintentionally\nlost afterwards.\n\n## Affected\n\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < c372ca227e16bace86f1df1fa4ae6849e2fcfa28`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < a71143590ce9764dbcb47617647592ff8b4d48bc`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 65770111a2d47c2b15e20b2ba92bb12198f289d4`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 015dc4a1e0c2cba551d4620eba13d26d5081dc34`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < ba9fa2ff5981589bb49094d3358c339b37c47f53`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 9faa6b69ad73f03c7bde53e07d75a28822dc9a1a`\n- `Linux >= 0110a4c43451533de1ea1bbdc57b5d452f9d8b25 < 486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae`\n- `Linux 4.20`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}