# CVE-2022-49174: linux: In the Linux kernel, the following vulnerability has been resolved:  ext4: fix ext4_mb_mark_bb() with flex_bg with fa...

CVE-2022-49174 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-49174, released February 26, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-49174
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0028
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 26, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  ext4: fix ext4_mb_mark_bb() with flex_bg with fast_commit  In case of flex_bg feature (which is by default enabled), extents for any given inode might span across blocks from two different block group. ext4_mb_mark_bb() only reads the buffer_head of block bitmap once for the starting block group, but it fails to read it again when the extent length boundary overflows to another block group. Then in this below loop it accesses memory beyond the block group bitmap buffer_head and results into a data abort.  	for (i = 0; i < clen; i++) 		if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state) 			already++;  This patch adds this functionality for checking block group boundary in ext4_mb_mark_bb() and update the buffer_head(bitmap_bh) for every different block group.  w/o this patch, I was easily able to hit a data access abort using Power platform.  <...> [   74.327662] EXT4-fs error (device loop3): ext4_mb_generate_buddy:1141: group 11, block bitmap and bg descriptor inconsistent: 21248 vs 23294 free clusters [   74.533214] EXT4-fs (loop3): shut down requested (2) [   74.536705] Aborting journal on device loop3-8. [   74.702705] BUG: Unable to handle kernel data access on read at 0xc00000005e980000 [   74.703727] Faulting instruction address: 0xc0000000007bffb8 cpu 0xd: Vector: 300 (Data Access) at [c000000015db7060]     pc: c0000000007bffb8: ext4_mb_mark_bb+0x198/0x5a0     lr: c0000000007bfeec: ext4_mb_mark_bb+0xcc/0x5a0     sp: c000000015db7300    msr: 800000000280b033    dar: c00000005e980000  dsisr: 40000000   current = 0xc000000027af6880   paca    = 0xc00000003ffd5200   irqmask: 0x03   irq_happened: 0x01     pid   = 5167, comm = mount <...> enter ? for help [c000000015db7380] c000000000782708 ext4_ext_clear_bb+0x378/0x410 [c000000015db7400] c000000000813f14 ext4_fc_replay+0x1794/0x2000 [c000000015db7580] c000000000833f7c do_one_pass+0xe9c/0x12a0 [c000000015db7710] c000000000834504 jbd2_journal_recover+0x184/0x2d0 [c000000015db77c0] c000000000841398 jbd2_journal_load+0x188/0x4a0 [c000000015db7880] c000000000804de8 ext4_fill_super+0x2638/0x3e10 [c000000015db7a40] c0000000005f8404 get_tree_bdev+0x2b4/0x350 [c000000015db7ae0] c0000000007ef058 ext4_get_tree+0x28/0x40 [c000000015db7b00] c0000000005f6344 vfs_get_tree+0x44/0x100 [c000000015db7b70] c00000000063c408 path_mount+0xdd8/0xe70 [c000000015db7c40] c00000000063c8f0 sys_mount+0x450/0x550 [c000000015db7d50] c000000000035770 system_call_exception+0x4a0/0x4e0 [c000000015db7e10] c00000000000c74c system_call_common+0xec/0x250

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.17.3-1 | [DEBIAN-CVE-2022-49174](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49174.md) | Feb 26, 2025 |
| Linux | linux Debian 13.5 (trixie) | 5.17.3-1 | [DEBIAN-CVE-2022-49174](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49174.md) | Feb 26, 2025 |
| Linux | linux Debian 14 | 5.17.3-1 | [DEBIAN-CVE-2022-49174](https://patchblox.com/security/data/fix/linux/debian-cve-2022-49174.md) | Feb 26, 2025 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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