CVE-2022-50021
ext4: block range must be validated before use in ext4_mb_clear_bb()
Reported by linux · Published June 18, 2025
In the Linux kernel, the following vulnerability has been resolved: ext4: block range must be validated before use in ext4_mb_clear_bb() Block range to free is validated in ext4_free_blocks() using ext4_inode_block_valid() and then it's passed to ext4_mb_clear_bb(). However in some situations on bigalloc file system the range might be adjusted after the validation in ext4_free_blocks() which can lead to troubles on corrupted file systems such as one found by syzkaller that resulted in the following BUG kernel BUG at fs/ext4/ext4.h:3319! PREEMPT SMP NOPTI CPU: 28 PID: 4243 Comm: repro Kdump: loaded Not tainted 5.19.0-rc6+ #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1.fc35 04/01/2014 RIP: 0010:ext4_free_blocks+0x95e/0xa90 Call Trace: <TASK> ? lock_timer_base+0x61/0x80 ? __es_remove_extent+0x5a/0x760 ? __mod_timer+0x256/0x380 ? ext4_ind_truncate_ensure_credits+0x90/0x220 ext4_clear_blocks+0x107/0x1b0 ext4_free_data+0x15b/0x170 ext4_ind_truncate+0x214/0x2c0 ? _raw_spin_unlock+0x15/0x30 ? ext4_discard_preallocations+0x15a/0x410 ? ext4_journal_check_start+0xe/0x90 ? __ext4_journal_start_sb+0x2f/0x110 ext4_truncate+0x1b5/0x460 ? __ext4_journal_start_sb+0x2f/0x110 ext4_evict_inode+0x2b4/0x6f0 evict+0xd0/0x1d0 ext4_enable_quotas+0x11f/0x1f0 ext4_orphan_cleanup+0x3de/0x430 ? proc_create_seq_private+0x43/0x50 ext4_fill_super+0x295f/0x3ae0 ? snprintf+0x39/0x40 ? sget_fc+0x19c/0x330 ? ext4_reconfigure+0x850/0x850 get_tree_bdev+0x16d/0x260 vfs_get_tree+0x25/0xb0 path_mount+0x431/0xa70 __x64_sys_mount+0xe2/0x120 do_syscall_64+0x5b/0x80 ? do_user_addr_fault+0x1e2/0x670 ? exc_page_fault+0x70/0x170 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7fdf4e512ace Fix it by making sure that the block range is properly validated before used every time it changes in ext4_free_blocks() or ext4_mb_clear_bb().
EPSS 0.20% · 10.3th percentile
Fixed versions
Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.
| Package | Ecosystem | Fixed in |
|---|---|---|
| linux_kernel | linux | 5.19.4, 5.15.103, 5.10.175 |
| Linux | Linux | a2522041d248a8c969cbbc97e1fc2cd8b4de120d, 560a2744cbbf03cac65a6394f9b0d99aa437c867 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | 84130193e0e6568dfdfb823f0e1e19aec80aff6e, 84130193e0e6568dfdfb823f0e1e19aec80aff6e, 84130193e0e6568dfdfb823f0e1e19aec80aff6e |
| Linux | Linux | 3.2, 0, 5.10.175 |
| Linux | Linux | 3.2, 6.0, 84130193e0e6568dfdfb823f0e1e19aec80aff6e |
| linux | linux_kernel | 3.2, 3.2, 3.2 |
Timeline
- Jun 18, 2025 CVE Published
- Jun 29, 2025 EPSS Score (29 in total, the first dated here)
- May 23, 2026 Coalition ESS Score
- Jun 2, 2026 Security Advisory (239 in total, the first dated here)
- Oct 13, 2026 CVE Updated
- Oct 18, 2026 Distribution Patch (228 in total, the first dated here)
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