{"id":"CVE-2026-74571","summary":"btrfs: skip global block reserve accounting for rescue mounts","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer dereference:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000100\n  RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs]\n  Call Trace:\n   fill_dummy_bgs+0xd4/0x120 [btrfs]\n   open_ctree+0xc6e/0x1ca0 [btrfs]\n   btrfs_get_tree+0x50d/0xa40 [btrfs]\n\nThe same crash occurs with a corrupted raid stripe tree root, via\nbtrfs_read_block_groups() instead of fill_dummy_bgs().\n\n[CAUSE]\nWith rescue=ibadroots, btrfs_read_roots() allows the mount to continue\nwhen either root cannot be read, leaving the corresponding root pointer\nNULL while its on-disk feature bit remains set.\n\nbtrfs_update_global_block_rsv() then dereferences the missing root based\non the feature bit alone.\n\n[FIX]\nRescue mounts are fully read-only and cannot start transactions, so the\nglobal reserve is never consumed. Under btrfs_is_full_ro(), mark the\nreserve as full and return before performing the accounting.\n\nAnd since we need to check if the fs is mount fully RO, export\nfs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h.\n\n[ Squash the fs_is_full_ro() export commit into this one. ]","modified":"2026-08-18T03:31:20.200070046Z","published":"2026-08-15T12:28:10.711Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74571.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74571.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74571"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8dbfc14fc736eb701089aff09645c3d4ad3decb1"},{"fixed":"076349e4c8d11f6b58c4549976a513b2b4dc6df2"},{"fixed":"51a0e8399858621442807a26057bcd1cd3ced046"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"cbec34d3021d47007a0334c634f7053dbaf93d02"},{"last_affected":"1e8087589b5cf6fa17adaf57b64cf1656d77dfec"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.1.43"},{"fixed":"6.2"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.4.8"},{"fixed":"6.5"}]}],"versions":["v6.4.7","v6.1.42","v6.4.6","v6.1.41","v6.4.5","v6.1.40","v6.4.4","v6.1.39","v6.4.3","v6.1.38","v6.4","v6.4.2","v6.4-rc7","v6.4-rc1","v6.4.1","v6.1.37","v6.1.36","v6.4-rc6","v6.1.35","v6.4-rc5","v6.4-rc3","v6.1.34","v6.4-rc4","v6.4-rc2","v6.1.33","v6.1.32","v6.1.31","v6.1.30","v6.1.29","v6.1.28","v6.3","v6.1.27","v6.1.26","v6.3-rc1","v6.1.25","v6.3-rc7","v6.3-rc2","v6.3-rc3","v6.3-rc5","v6.3-rc6","v6.3-rc4","v6.1.24","v6.2-rc6","v6.1.23","v6.1.22","v6.1.21","v6.1.20","v6.1.19","v6.1.18","v6.1.17","v6.1.16","v6.1.15","v6.2-rc1","v6.2","v6.1.14","v6.1.13","v6.2-rc2","v6.2-rc8","v6.1.12","v6.2-rc5","v6.2-rc4","v6.1.11","v6.2-rc7","v6.1.10","v6.2-rc3","v6.1.9","v6.1.8","v6.1.7","v6.1.6","v6.1-rc1","v6.1.5","v6.1.4","v6.1.3","v6.1.2","v6.1.1","v6.1","v6.1-rc8","v6.1-rc3","v6.1-rc6","v6.1-rc7","v6.1-rc4","v6.1-rc2","v6.1-rc5","v6.0-rc1","v6.0","v6.0-rc7","v6.0-rc3","v6.0-rc2","v6.0-rc6","v6.0-rc4","v6.0-rc5","v5.19","v5.19-rc1","v5.19-rc5","v5.19-rc8","v5.19-rc6","v5.18","v5.19-rc2","v5.19-rc7","v5.19-rc3","v5.19-rc4","v5.18-rc1","v5.18-rc7","v5.18-rc2","v5.18-rc5","v5.17","v5.18-rc4","v5.18-rc3","v5.18-rc6","v5.17-rc6","v5.17-rc4","v5.17-rc8","v5.17-rc7","v5.17-rc1","v5.17-rc3","v5.17-rc2","v5.17-rc5","v5.16","v5.16-rc1","v5.16-rc8","v5.16-rc5","v5.16-rc6","v5.16-rc7","v5.16-rc3","v5.16-rc2","v5.16-rc4","v5.15","v5.15-rc2","v5.15-rc1","v5.15-rc4","v5.15-rc7","v5.15-rc3","v5.15-rc5","v5.15-rc6","v5.14","v5.14-rc3","v5.14-rc1","v5.14-rc2","v5.14-rc7","v5.14-rc6","v5.13-rc1","v5.14-rc5","v5.14-rc4","v5.13","v5.13-rc6","v5.13-rc7","v5.13-rc3","v5.13-rc2","v5.13-rc4","v5.13-rc5","v5.12","v5.12-rc2","v5.12-rc1-dontuse","v5.12-rc1","v5.12-rc8","v5.12-rc3","v5.12-rc7","v5.12-rc5","v5.12-rc6","v5.12-rc4","v5.10","v5.11","v5.11-rc3","v5.11-rc7","v5.11-rc6","v5.11-rc5","v5.11-rc1","v5.11-rc4","v5.11-rc2","v5.10-rc1","v5.10-rc7","v5.10-rc4","v5.10-rc3","v5.10-rc6","v5.9","v5.10-rc2","v5.10-rc5","v5.9-rc1","v5.9-rc7","v5.9-rc8","v5.9-rc6","v5.9-rc4","v5.9-rc5","v5.9-rc3","v5.9-rc2","v5.8","v5.7","v5.8-rc2","v5.8-rc1","v5.8-rc7","v5.8-rc5","v5.8-rc3","v5.8-rc4","v5.8-rc6","v5.7-rc4","v5.7-rc7","v5.7-rc1","v5.7-rc3","v5.7-rc2","v5.7-rc5","v5.7-rc6","v5.6","v5.6-rc1","v5.6-rc7","v5.6-rc6","v5.6-rc3","v5.6-rc4","v5.6-rc2","v5.6-rc5","v5.5","v5.5-rc5","v5.5-rc7","v5.5-rc2","v5.5-rc1","v5.4","v5.5-rc4","v5.5-rc3","v5.5-rc6","v5.4-rc1","v5.4-rc6","v5.4-rc3","v5.4-rc4","v5.4-rc8","v5.4-rc7","v5.4-rc5","v5.3","v5.4-rc2","v5.3-rc5","v5.3-rc1","v5.3-rc2","v5.3-rc3","v5.3-rc8","v5.3-rc7","v5.3-rc4","v5.2","v5.3-rc6","v5.2-rc2","v5.2-rc7","v5.2-rc4","v5.2-rc1","v5.2-rc5","v5.2-rc6","v5.2-rc3","v5.1","v5.0-rc8","v5.1-rc7","v5.1-rc1","v5.1-rc6","v5.1-rc5","v5.0","v5.1-rc3","v5.1-rc2","v5.1-rc4","v5.0-rc1","v5.0-rc4","v5.0-rc3","v5.0-rc6","v5.0-rc7","v5.0-rc2","v5.0-rc5","v4.20-rc1","v4.19","v4.20","v4.20-rc7","v4.20-rc5","v4.20-rc6","v4.20-rc4","v4.20-rc2","v4.20-rc3","v4.19-rc2","v4.19-rc8","v4.19-rc4","v4.19-rc1","v4.19-rc7","v4.19-rc6","v4.19-rc5","v4.19-rc3","v4.18","v4.18-rc1","v4.18-rc8","v4.18-rc2","v4.18-rc5","v4.18-rc6","v4.18-rc7","v4.17","v4.18-rc3","v4.18-rc4","v4.17-rc1","v4.17-rc2","v4.17-rc7","v4.17-rc3","v4.17-rc4","v4.16","v4.17-rc6","v4.17-rc5","v4.16-rc7","v4.16-rc4","v4.16-rc1","v4.16-rc2","v4.16-rc5","v4.16-rc3","v4.16-rc6","v4.14","v4.15","v4.15-rc1","v4.15-rc4","v4.15-rc9","v4.15-rc8","v4.15-rc7","v4.15-rc3","v4.15-rc2","v4.15-rc5","v4.15-rc6","v4.14-rc1","v4.14-rc7","v4.14-rc3","v4.13","v4.14-rc8"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