CVE-2022-49708 - CVE House
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Status published Medium CVE-2022-49708

ext4: fix bug_on ext4_mb_use_inode_pa

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix bug_on ext4_mb_use_inode_pa Hulk Robot reported a BUG_ON: ================================================================== kernel BUG at fs/ext4/mballoc.c:3211! [...] RIP: 0010:ext4_mb_mark_diskspace_used.cold+0x85/0x136f [...] Call Trace: ext4_mb_new_blocks+0x9df/0x5d30 ext4_ext_map_blocks+0x1803/0x4d80 ext4_map_blocks+0x3a4/0x1a10 ext4_writepages+0x126d/0x2c30 do_writepages+0x7f/0x1b0 __filemap_fdatawrite_range+0x285/0x3b0 file_write_and_wait_range+0xb1/0x140 ext4_sync_file+0x1aa/0xca0 vfs_fsync_range+0xfb/0x260 do_fsync+0x48/0xa0 [...] ================================================================== Above issue may happen as follows: ------------------------------------- do_fsync vfs_fsync_range ext4_sync_file file_write_and_wait_range __filemap_fdatawrite_range do_writepages ext4_writepages mpage_map_and_submit_extent mpage_map_one_extent ext4_map_blocks ext4_mb_new_blocks ext4_mb_normalize_request >>> start + size <= ac->ac_o_ex.fe_logical ext4_mb_regular_allocator ext4_mb_simple_scan_group ext4_mb_use_best_found ext4_mb_new_preallocation ext4_mb_new_inode_pa ext4_mb_use_inode_pa >>> set ac->ac_b_ex.fe_len <= 0 ext4_mb_mark_diskspace_used >>> BUG_ON(ac->ac_b_ex.fe_len <= 0); we can easily reproduce this problem with the following commands: `fallocate -l100M disk` `mkfs.ext4 -b 1024 -g 256 disk` `mount disk /mnt` `fsstress -d /mnt -l 0 -n 1000 -p 1` The size must be smaller than or equal to EXT4_BLOCKS_PER_GROUP. Therefore, "start + size <= ac->ac_o_ex.fe_logical" may occur when the size is truncated. So start should be the start position of the group where ac_o_ex.fe_logical is located after alignment. In addition, when the value of fe_logical or EXT4_BLOCKS_PER_GROUP is very large, the value calculated by start_off is more accurate.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

Linux
Vulnerable Versions:
fc6c2da174edd7a7b760b12c60d432d300e05cca, cd648b8a8fd5071d232242d5ee7ee3c0815776af, f213db429b883a2d5403de0b1ce92fb7d7ee979e, 98f58e05231f835dfb09359e3b5e3a886fe8f189, c1664e9bcf6291c0ceb8599f57c8cf493526abe6, 37cf4ab1ba60c30ca9fd0fe3b9993b24cb87886a, 75f37dab088eb84ff25a49e59371f01ea3f44aa7, 8774c73cf6963310395823ed7077ea12943ea0f3, c4fbdc0124799f1772f4d886b7f2e1a6f881d195, 4.9.14, 3.2.89, 3.10.107, 3.12.72, 3.16.44, 4.1.40, 4.4.53, 4.10.2, 4.11, 0, 4.9.320, 4.14.285, 4.19.249, 5.4.200, 5.10.124, 5.15.49, 5.18.6, 5.19

Timeline

Official Publish: February 26th, 2025
Last Modified: May 23rd, 2026
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weaknesses (CWE)

No CWE data available

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.