{"id":"CVE-2022-50021","title":"ext4: block range must be validated before use in ext4_mb_clear_bb()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: block range must be validated before use in ext4_mb_clear_bb()\n\nBlock range to free is validated in ext4_free_blocks() using\next4_inode_block_valid() and then it'…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < 7550aade978371ac582f6d43b14c4cb89ca54463","Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < 560a2744cbbf03cac65a6394f9b0d99aa437c867","Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < a2522041d248a8c969cbbc97e1fc2cd8b4de120d","Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < 1e1c2b86ef86a8477fd9b9a4f48a6bfe235606f6","Linux 3.2"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T19:53:08.795705Z"},"published":"2025-06-18","updated":"2026-11-05","sourceUpdated":"2026-11-05T20:00:14.107Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2022-50021","references":[{"url":"https://git.kernel.org/stable/c/7550aade978371ac582f6d43b14c4cb89ca54463"},{"url":"https://git.kernel.org/stable/c/560a2744cbbf03cac65a6394f9b0d99aa437c867"},{"url":"https://git.kernel.org/stable/c/a2522041d248a8c969cbbc97e1fc2cd8b4de120d"},{"url":"https://git.kernel.org/stable/c/1e1c2b86ef86a8477fd9b9a4f48a6bfe235606f6"}],"tags":["cve.org"],"epss":0.00204,"epssPercentile":0.10397,"ingestedAt":"2026-11-05T22:38:31.635Z","slug":"CVE-2022-50021","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\next4: block range must be validated before use in ext4_mb_clear_bb()\n\nBlock range to free is validated in ext4_free_blocks() using\next4_inode_block_valid() and then it's passed to ext4_mb_clear_bb().\nHowever in some situations on bigalloc file system the range might be\nadjusted after the validation in ext4_free_blocks() which can lead to\ntroubles on corrupted file systems such as one found by syzkaller that\nresulted in the following BUG\n\nkernel BUG at fs/ext4/ext4.h:3319!\nPREEMPT SMP NOPTI\nCPU: 28 PID: 4243 Comm: repro Kdump: loaded Not tainted 5.19.0-rc6+ #1\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1.fc35 04/01/2014\nRIP: 0010:ext4_free_blocks+0x95e/0xa90\nCall Trace:\n <TASK>\n ? lock_timer_base+0x61/0x80\n ? __es_remove_extent+0x5a/0x760\n ? __mod_timer+0x256/0x380\n ? ext4_ind_truncate_ensure_credits+0x90/0x220\n ext4_clear_blocks+0x107/0x1b0\n ext4_free_data+0x15b/0x170\n ext4_ind_truncate+0x214/0x2c0\n ? _raw_spin_unlock+0x15/0x30\n ? ext4_discard_preallocations+0x15a/0x410\n ? ext4_journal_check_start+0xe/0x90\n ? __ext4_journal_start_sb+0x2f/0x110\n ext4_truncate+0x1b5/0x460\n ? __ext4_journal_start_sb+0x2f/0x110\n ext4_evict_inode+0x2b4/0x6f0\n evict+0xd0/0x1d0\n ext4_enable_quotas+0x11f/0x1f0\n ext4_orphan_cleanup+0x3de/0x430\n ? proc_create_seq_private+0x43/0x50\n ext4_fill_super+0x295f/0x3ae0\n ? snprintf+0x39/0x40\n ? sget_fc+0x19c/0x330\n ? ext4_reconfigure+0x850/0x850\n get_tree_bdev+0x16d/0x260\n vfs_get_tree+0x25/0xb0\n path_mount+0x431/0xa70\n __x64_sys_mount+0xe2/0x120\n do_syscall_64+0x5b/0x80\n ? do_user_addr_fault+0x1e2/0x670\n ? exc_page_fault+0x70/0x170\n entry_SYSCALL_64_after_hwframe+0x46/0xb0\nRIP: 0033:0x7fdf4e512ace\n\nFix it by making sure that the block range is properly validated before\nused every time it changes in ext4_free_blocks() or ext4_mb_clear_bb().\n\n## Affected\n\n- `Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < 7550aade978371ac582f6d43b14c4cb89ca54463`\n- `Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < 560a2744cbbf03cac65a6394f9b0d99aa437c867`\n- `Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < a2522041d248a8c969cbbc97e1fc2cd8b4de120d`\n- `Linux >= 84130193e0e6568dfdfb823f0e1e19aec80aff6e < 1e1c2b86ef86a8477fd9b9a4f48a6bfe235606f6`\n- `Linux 3.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}