{"id":"DEBIAN-CVE-2026-23249","details":"In the Linux kernel, the following vulnerability has been resolved:  xfs: check for deleted cursors when revalidating two btrees  The free space and inode btree repair functions will rebuild both btrees at the same time, after which it needs to evaluate both btrees to confirm that the corruptions are gone.  However, Jiaming Zhang ran syzbot and produced a crash in the second xchk_allocbt call.  His root-cause analysis is as follows (with minor corrections):   In xrep_revalidate_allocbt(), xchk_allocbt() is called twice (first  for BNOBT, second for CNTBT). The cause of this issue is that the  first call nullified the cursor required by the second call.   Let's first enter xrep_revalidate_allocbt() via following call chain:   xfs_file_ioctl() -\u003e  xfs_ioc_scrubv_metadata() -\u003e  xfs_scrub_metadata() -\u003e  `sc-\u003eops-\u003erepair_eval(sc)` -\u003e  xrep_revalidate_allocbt()   xchk_allocbt() is called twice in this function. In the first call:   /* Note that sc-\u003esm-\u003esm_type is XFS_SCRUB_TYPE_BNOPT now */  xchk_allocbt() -\u003e  xchk_btree() -\u003e  `bs-\u003escrub_rec(bs, recp)` -\u003e  xchk_allocbt_rec() -\u003e  xchk_allocbt_xref() -\u003e  xchk_allocbt_xref_other()   since sm_type is XFS_SCRUB_TYPE_BNOBT, pur is set to &sc-\u003esa.cnt_cur.  Kernel called xfs_alloc_get_rec() and returned -EFSCORRUPTED. Call  chain:   xfs_alloc_get_rec() -\u003e  xfs_btree_get_rec() -\u003e  xfs_btree_check_block() -\u003e  (XFS_IS_CORRUPT || XFS_TEST_ERROR), the former is false and the latter  is true, return -EFSCORRUPTED. This should be caused by  ioctl$XFS_IOC_ERROR_INJECTION I guess.   Back to xchk_allocbt_xref_other(), after receiving -EFSCORRUPTED from  xfs_alloc_get_rec(), kernel called xchk_should_check_xref(). In this  function, *curpp (points to sc-\u003esa.cnt_cur) is nullified.   Back to xrep_revalidate_allocbt(), since sc-\u003esa.cnt_cur has been  nullified, it then triggered null-ptr-deref via xchk_allocbt() (second  call) -\u003e xchk_btree().  So.  The bnobt revalidation failed on a cross-reference attempt, so we deleted the cntbt cursor, and then crashed when we tried to revalidate the cntbt.  Therefore, check for a null cntbt cursor before that revalidation, and mark the repair incomplete.  Also we can ignore the second tree entirely if the first tree was rebuilt but is already corrupt.  Apply the same fix to xrep_revalidate_iallocbt because it has the same problem.","modified":"2026-08-27T23:05:47.305429119Z","published":"2026-03-18T18:16:22.787Z","upstream":["CVE-2026-23249"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-23249"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.85-1"}]}],"versions":["6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1~bpo12+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23249.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.19.6-1"}]}],"versions":["6.12.100-1","6.12.101-1","6.12.105-1","6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1","6.12.94-1~bpo12+1","6.12.95-1","6.12.95-1~bpo12+1","6.12.96-1","6.13.10-1~exp1","6.13.11-1~exp1","6.13.2-1~exp1","6.13.3-1~exp1","6.13.4-1~exp1","6.13.5-1~exp1","6.13.6-1~exp1","6.13.7-1~exp1","6.13.8-1~exp1","6.13.9-1~exp1","6.13~rc6-1~exp1","6.13~rc7-1~exp1","6.14.3-1~exp1","6.14.5-1~exp1","6.14.6-1~exp1","6.15-1~exp1","6.15.1-1~exp1","6.15.2-1~exp1","6.15.3-1~exp1","6.15.4-1~exp1","6.15.5-1~exp1","6.15.6-1~exp1","6.15~rc7-1~exp1","6.16-1~exp1","6.16.1-1~exp1","6.16.10-1","6.16.11-1","6.16.12-1","6.16.12-1~bpo13+1","6.16.12-2","6.16.3-1","6.16.3-1~bpo13+1","6.16.5-1","6.16.6-1","6.16.7-1","6.16.8-1","6.16.9-1","6.16~rc7-1~exp1","6.17.10-1","6.17.11-1","6.17.12-1","6.17.13-1","6.17.13-1~bpo13+1","6.17.2-1~exp1","6.17.5-1~exp1","6.17.6-1","6.17.7-1","6.17.7-2","6.17.8-1","6.17.8-1~bpo13+1","6.17.9-1","6.18.1-1~exp1","6.18.10-1","6.18.12-1","6.18.12-1~bpo13+1","6.18.13-1","6.18.14-1","6.18.15-1","6.18.15-1~bpo13+1","6.18.2-1~exp1","6.18.3-1","6.18.5-1","6.18.5-1~bpo13+1","6.18.8-1","6.18.9-1","6.18.9-1~bpo13+1","6.18~rc4-1~exp1","6.18~rc4-1~exp2","6.18~rc5-1~exp1","6.18~rc6-1~exp1","6.18~rc7-1~exp1","6.19-1~exp1","6.19.2-1~exp1","6.19.3-1~exp1","6.19.4-1~exp1","6.19.5-1~exp1","6.19~rc4-1~exp1","6.19~rc5-1~exp1","6.19~rc6-1~exp1","6.19~rc7-1~exp1","6.19~rc8-1~exp1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23249.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}