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/[email protected]/
“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).”