{"id":"CVE-2026-97549","summary":"xfs: fix under-reservation of blocks when repairing sf directories","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: fix under-reservation of blocks when repairing sf directories\n\nWhilst running QA on XFS for-next as of 7.3-rc2 with MKFS_OPTIONS=\"-n\nsize=8192\", I observed the following (trimmed) dmesg splat:\n\n XFS: Assertion failed: args-\u003etotal \u003e= dp-\u003ei_nblocks - nblks, file: fs/xfs/libxfs/xfs_da_btree.c, line: 2387\n WARNING: fs/xfs/xfs_message.c:104 at assfail+0x46/0x4a [xfs], CPU#0: xfs_scrub/1426511\n CPU: 0 UID: 0 PID: 1426511 Comm: xfs_scrub Tainted: G        W           7.3.0-rc2-djwx #rc2 PREEMPT(lazy)  6e418570b606a39783b0e7e7b30dc407b965f9e8\n Tainted: [W]=WARN\n RIP: 0010:assfail+0x46/0x4a [xfs]\n RSP: 0018:ffffc900010d7890 EFLAGS: 00010246\n RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000ffffffd1\n RDX: 0000000000000000 RSI: 0000000000000021 RDI: ffffffffa059fd38\n RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000\n R10: 000000000000000a R11: 000000007fffffff R12: ffffc900010d7940\n R13: ffff888368d8f980 R14: ffffc900010d7a48 R15: ffffc900010d78d0\n FS:  00007f445c5ce680(0000) GS:ffff8884a97ea000(0000) knlGS:0000000000000000\n CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 00007f443803b9a8 CR3: 0000000107a4b000 CR4: 00000000003506f0\n Call Trace:\n  \u003cTASK\u003e\n  xfs_da_grow_inode_int+0x2e0/0x300 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xfs_dir2_grow_inode+0x6e/0x150 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xfs_dir2_sf_to_block+0x149/0x870 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xrep_dir_swap_prep+0xe2/0x110 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xrep_dir_swap+0xfb/0x2f0 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xrep_dir_rebuild_tree+0x99/0x100 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xrep_directory+0x83/0x1c0 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xrep_attempt+0x4f/0x1e0 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xfs_scrub_metadata+0x393/0x5b0 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xfs_ioc_scrubv_metadata+0x306/0x570 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  xfs_file_ioctl+0xa4f/0x1150 [xfs 5de2257e14108c136f11317e6bbb8ac77efd392c]\n  __x64_sys_ioctl+0x76/0xc0\n  do_syscall_64+0x7a/0x3b0\n  entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\nThis is a consequence of commit 0fe77e57588b98, which added the\nfollowing assertion to xfs_da_grow_inode_int:\n\n ASSERT(args-\u003etotal \u003e= dp-\u003ei_nblocks - nblks);\n\nTracing this back to xrep_dir_swap_prep, I noticed that the xfs_da_args\nobject that's passed to xfs_dir2_sf_to_block sets args-\u003etotal to 1.\nThis is incorrect because mkfs set the directory block size to 8k and\nthe filesystem block size to 4k.  In other words, args-\u003etotal should be\n2 here, not 1.\n\nDave Chinner tripped over the same problem with the same branch through\na different channel -- his test setup set the fs block size to 1k, in\nwhich case the directory block size is still set to 4k.  Here,\nargs-\u003etotal should be 4.\n\nChanging the assignment of args-\u003etotal to sc-\u003emp-\u003em_dir_geo-\u003efsbcount\nmakes the assertion go away, but that isn't a complete fix.  In\nxrep_tempexch_estimate, we also incorrectly assume that a shortform\nconversion requires 1 fsblock when it should be m_dir_geo-\u003efsbcount.\nWithout that, we can under-reserve space in the transaction and cause a\nfilesystem shutdown.\n\nNote that the xfs_dabuf_nfsb helper will compute the correct value for\ndirectories and xattr, so we use that instead of open-coding the logic.\nAlso fix xrep_xattr_swap_prep to assign args-\u003etotal via xfs_dabuf_nfsb\nto avoid one logic bomb if we ever support multi-fsblock attrs.\n\nTripped-by: 0fe77e57588b98 (\"xfs: assert the reservation covers each da fork growth\")","modified":"2026-09-26T03:48:29.659414913Z","published":"2026-09-25T10:21:42.852Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97549.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4d3c07591534517c633945c8d8e6526f10e3fabc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b8f46ca5cbd629ffb91489ad7f970b3837835b0a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b950e84acd072ac648ace4fea53c0b1212da4b2c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97549.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97549"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"629fdaf5f5b1b7f7107ed4de04e0991a99501ced"},{"fixed":"b8f46ca5cbd629ffb91489ad7f970b3837835b0a"},{"fixed":"b950e84acd072ac648ace4fea53c0b1212da4b2c"},{"fixed":"4d3c07591534517c633945c8d8e6526f10e3fabc"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97549.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.10.0"},{"fixed":"6.18.54"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97549.json"}}],"schema_version":"1.9.0"}