# CVE-2021-47117: linux: In the Linux kernel, the following vulnerability has been resolved:  ext4: fix bug on in ext4_es_cache_extent as ext4...

CVE-2021-47117 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47117, released March 15, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47117
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 15, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  ext4: fix bug on in ext4_es_cache_extent as ext4_split_extent_at failed  We got follow bug_on when run fsstress with injecting IO fault: [130747.323114] kernel BUG at fs/ext4/extents_status.c:762! [130747.323117] Internal error: Oops - BUG: 0 [#1] SMP ...... [130747.334329] Call trace: [130747.334553]  ext4_es_cache_extent+0x150/0x168 [ext4] [130747.334975]  ext4_cache_extents+0x64/0xe8 [ext4] [130747.335368]  ext4_find_extent+0x300/0x330 [ext4] [130747.335759]  ext4_ext_map_blocks+0x74/0x1178 [ext4] [130747.336179]  ext4_map_blocks+0x2f4/0x5f0 [ext4] [130747.336567]  ext4_mpage_readpages+0x4a8/0x7a8 [ext4] [130747.336995]  ext4_readpage+0x54/0x100 [ext4] [130747.337359]  generic_file_buffered_read+0x410/0xae8 [130747.337767]  generic_file_read_iter+0x114/0x190 [130747.338152]  ext4_file_read_iter+0x5c/0x140 [ext4] [130747.338556]  __vfs_read+0x11c/0x188 [130747.338851]  vfs_read+0x94/0x150 [130747.339110]  ksys_read+0x74/0xf0  This patch's modification is according to Jan Kara's suggestion in: https://patchwork.ozlabs.org/project/linux-ext4/patch/20210428085158.3728201-1-yebin10@huawei.com/ "I see. Now I understand your patch. Honestly, seeing how fragile is trying to fix extent tree after split has failed in the middle, I would probably go even further and make sure we fix the tree properly in case of ENOSPC and EDQUOT (those are easily user triggerable).  Anything else indicates a HW problem or fs corruption so I'd rather leave the extent tree as is and don't try to fix it (which also means we will not create overlapping extents)."

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.46-1 | [DEBIAN-CVE-2021-47117](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47117.md) | Mar 15, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.46-1 | [DEBIAN-CVE-2021-47117](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47117.md) | Mar 15, 2024 |
| Linux | linux Debian 14 | 5.10.46-1 | [DEBIAN-CVE-2021-47117](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47117.md) | Mar 15, 2024 |

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