CVE-2021-47117

MEDIUMCVSS 5.5/10EPSS 0.24%

Last modified

CVE-2021-47117 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. 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. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

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)."

Metrics

CVSS 3.1
5.5/10

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

EPSS Probability
0.24%

15.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel< 4.4.272
LinuxLinux Kernel>= 4.5, < 4.9.272
LinuxLinux Kernel>= 4.10, < 4.14.236
LinuxLinux Kernel>= 4.15, < 4.19.194
LinuxLinux Kernel>= 4.20, < 5.4.125
LinuxLinux Kernel>= 5.5, < 5.10.43
LinuxLinux Kernel>= 5.11, < 5.12.10
LinuxLinux Kernel5.13Rc1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2021-47117?
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)."
How severe is CVE-2021-47117?
CVE-2021-47117 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.
How do I fix CVE-2021-47117?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST