{"cve":"CVE-2024-26727","nvd":{"published":"2024-04-03T15:15:54.367","modified":"2026-06-17T07:18:11.373","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() if the newly created subvolume already got read\n\n[BUG]\nThere is a syzbot crash, triggered by the ASSERT() during subvolume\ncreation:\n\n assertion failed: !anon_dev, in fs/btrfs/disk-io.c:1319\n ------------[ cut here ]------------\n kernel BUG at fs/btrfs/disk-io.c:1319!\n invalid opcode: 0000 [#1] PREEMPT SMP KASAN\n RIP: 0010:btrfs_get_root_ref.part.0+0x9aa/0xa60\n  <TASK>\n  btrfs_get_new_fs_root+0xd3/0xf0\n  create_subvol+0xd02/0x1650\n  btrfs_mksubvol+0xe95/0x12b0\n  __btrfs_ioctl_snap_create+0x2f9/0x4f0\n  btrfs_ioctl_snap_create+0x16b/0x200\n  btrfs_ioctl+0x35f0/0x5cf0\n  __x64_sys_ioctl+0x19d/0x210\n  do_syscall_64+0x3f/0xe0\n  entry_SYSCALL_64_after_hwframe+0x63/0x6b\n ---[ end trace 0000000000000000 ]---\n\n[CAUSE]\nDuring create_subvol(), after inserting root item for the newly created\nsubvolume, we would trigger btrfs_get_new_fs_root() to get the\nbtrfs_root of that subvolume.\n\nThe idea here is, we have preallocated an anonymous device number for\nthe subvolume, thus we can assign it to the new subvolume.\n\nBut there is really nothing preventing things like backref walk to read\nthe new subvolume.\nIf that happens before we call btrfs_get_new_fs_root(), the subvolume\nwould be read out, with a new anonymous device number assigned already.\n\nIn that case, we would trigger ASSERT(), as we really expect no one to\nread out that subvolume (which is not yet accessible from the fs).\nBut things like backref walk is still possible to trigger the read on\nthe subvolume.\n\nThus our assumption on the ASSERT() is not correct in the first place.\n\n[FIX]\nFix it by removing the ASSERT(), and just free the @anon_dev, reset it\nto 0, and continue.\n\nIf the subvolume tree is read out by something else, it should have\nalready get a new anon_dev assigned thus we only need to free the\npreallocated one.","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-617"],"references":["https://git.kernel.org/stable/c/3f5d47eb163bceb1b9e613c9003bae5fefc0046f","https://git.kernel.org/stable/c/5a172344bfdabb46458e03708735d7b1a918c468","https://git.kernel.org/stable/c/66b317a2fc45b2ef66527ee3f8fa08fb5beab88d","https://git.kernel.org/stable/c/833775656d447c545133a744a0ed1e189ce61430","https://git.kernel.org/stable/c/e03ee2fe873eb68c1f9ba5112fee70303ebf9dfb"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:47:51.568503435+00:00"},"epss":{"cve":"CVE-2024-26727","score":0.00228,"percentile":0.13609,"date":"2026-11-01"},"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."]}