{"cve":"CVE-2024-26658","nvd":{"published":"2024-04-02T07:15:42.903","modified":"2026-06-17T07:18:01.400","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbcachefs: grab s_umount only if snapshotting\n\nWhen I was testing mongodb over bcachefs with compression,\nthere is a lockdep warning when snapshotting mongodb data volume.\n\n$ cat test.sh\nprog=bcachefs\n\n$prog subvolume create /mnt/data\n$prog subvolume create /mnt/data/snapshots\n\nwhile true;do\n    $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s)\n    sleep 1s\ndone\n\n$ cat /etc/mongodb.conf\nsystemLog:\n  destination: file\n  logAppend: true\n  path: /mnt/data/mongod.log\n\nstorage:\n  dbPath: /mnt/data/\n\nlockdep reports:\n[ 3437.452330] ======================================================\n[ 3437.452750] WARNING: possible circular locking dependency detected\n[ 3437.453168] 6.7.0-rc7-custom+ #85 Tainted: G            E\n[ 3437.453562] ------------------------------------------------------\n[ 3437.453981] bcachefs/35533 is trying to acquire lock:\n[ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190\n[ 3437.454875]\n               but task is already holding lock:\n[ 3437.455268] ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]\n[ 3437.456009]\n               which lock already depends on the new lock.\n\n[ 3437.456553]\n               the existing dependency chain (in reverse order) is:\n[ 3437.457054]\n               -> #3 (&type->s_umount_key#48){.+.+}-{3:3}:\n[ 3437.457507]        down_read+0x3e/0x170\n[ 3437.457772]        bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]\n[ 3437.458206]        __x64_sys_ioctl+0x93/0xd0\n[ 3437.458498]        do_syscall_64+0x42/0xf0\n[ 3437.458779]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.459155]\n               -> #2 (&c->snapshot_create_lock){++++}-{3:3}:\n[ 3437.459615]        down_read+0x3e/0x170\n[ 3437.459878]        bch2_truncate+0x82/0x110 [bcachefs]\n[ 3437.460276]        bchfs_truncate+0x254/0x3c0 [bcachefs]\n[ 3437.460686]        notify_change+0x1f1/0x4a0\n[ 3437.461283]        do_truncate+0x7f/0xd0\n[ 3437.461555]        path_openat+0xa57/0xce0\n[ 3437.461836]        do_filp_open+0xb4/0x160\n[ 3437.462116]        do_sys_openat2+0x91/0xc0\n[ 3437.462402]        __x64_sys_openat+0x53/0xa0\n[ 3437.462701]        do_syscall_64+0x42/0xf0\n[ 3437.462982]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.463359]\n               -> #1 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}:\n[ 3437.463843]        down_write+0x3b/0xc0\n[ 3437.464223]        bch2_write_iter+0x5b/0xcc0 [bcachefs]\n[ 3437.464493]        vfs_write+0x21b/0x4c0\n[ 3437.464653]        ksys_write+0x69/0xf0\n[ 3437.464839]        do_syscall_64+0x42/0xf0\n[ 3437.465009]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.465231]\n               -> #0 (sb_writers#10){.+.+}-{0:0}:\n[ 3437.465471]        __lock_acquire+0x1455/0x21b0\n[ 3437.465656]        lock_acquire+0xc6/0x2b0\n[ 3437.465822]        mnt_want_write+0x46/0x1a0\n[ 3437.465996]        filename_create+0x62/0x190\n[ 3437.466175]        user_path_create+0x2d/0x50\n[ 3437.466352]        bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs]\n[ 3437.466617]        __x64_sys_ioctl+0x93/0xd0\n[ 3437.466791]        do_syscall_64+0x42/0xf0\n[ 3437.466957]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.467180]\n               other info that might help us debug this:\n\n[ 3437.469670] 2 locks held by bcachefs/35533:\n               other info that might help us debug this:\n\n[ 3437.467507] Chain exists of:\n                 sb_writers#10 --> &c->snapshot_create_lock --> &type->s_umount_key#48\n\n[ 3437.467979]  Possible unsafe locking scenario:\n\n[ 3437.468223]        CPU0                    CPU1\n[ 3437.468405]        ----                    ----\n[ 3437.468585]   rlock(&type->s_umount_key#48);\n[ 3437.468758]                                lock(&c->snapshot_create_lock);\n[ 3437.469030]                                lock(&type->s_umount_key#48);\n[ 3437.469291]   rlock(sb_writers#10);\n[ 3437.469434]\n                *** DEADLOCK ***\n\n[ 3437.469\n---truncated---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-667"],"references":["https://git.kernel.org/stable/c/2acc59dd88d27ad69b66ded80df16c042b04eeec","https://git.kernel.org/stable/c/5b41d3fd04c6757b9c2a60a0c5b2609cae9999df","https://git.kernel.org/stable/c/2acc59dd88d27ad69b66ded80df16c042b04eeec","https://git.kernel.org/stable/c/5b41d3fd04c6757b9c2a60a0c5b2609cae9999df"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:47:51.568503435+00:00"},"epss":{"cve":"CVE-2024-26658","score":0.00148,"percentile":0.03966,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}