CVE-2021-47335: f2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid racing on fsyncentryslab by multi filesystem instances
As syzbot reported, there is an use-after-free issue during f2fs recovery:
Use-after-free write at 0xffff88823bc16040 (in kfence-#10): kmemcachedestroy+0x1f/0x120 mm/slabcommon.c:486 f2fsrecoverfsyncdata+0x75b0/0x8380 fs/f2fs/recovery.c:869 f2fsfillsuper+0x9393/0xa420 fs/f2fs/super.c:3945 mountbdev+0x26c/0x3a0 fs/super.c:1367 legacygettree+0xea/0x180 fs/fscontext.c:592 vfsgettree+0x86/0x270 fs/super.c:1497 donewmount fs/namespace.c:2905 [inline] pathmount+0x196f/0x2be0 fs/namespace.c:3235 domount fs/namespace.c:3248 [inline] dosysmount fs/namespace.c:3456 [inline] sesysmount+0x2f9/0x3b0 fs/namespace.c:3433 dosyscall64+0x3f/0xb0 arch/x86/entry/common.c:47 entrySYSCALL64afterhwframe+0x44/0xae
The root cause is multi f2fs filesystem instances can race on accessing global fsyncentryslab pointer, result in use-after-free issue of slab cache, fixes to init/destroy this slab cache only once during module init/destroy procedure to avoid this issue.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2021-47335?
CVE-2021-47335 has a severity rating of medium due to the use-after-free vulnerability in the Linux f2fs filesystem.
How do I fix CVE-2021-47335?
To fix CVE-2021-47335, you should upgrade to the patched Linux kernel that addresses this vulnerability.
What systems are affected by CVE-2021-47335?
CVE-2021-47335 affects the Linux kernel and specifically the f2fs filesystem implementations.
Can CVE-2021-47335 lead to system crashes?
Yes, CVE-2021-47335 can potentially lead to system crashes due to the use-after-free condition.
Is CVE-2021-47335 exploitable remotely?
CVE-2021-47335 is not typically considered remotely exploitable unless specific configurations or use cases allow for it.