Bug 2315192 (CVE-2024-46840)

Summary: CVE-2024-46840 kernel: btrfs: clean up our handling of refs == 0 in snapshot delete
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Bug Depends On: 2315266    
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Description OSIDB Bzimport 2024-09-27 13:22:25 UTC 
In the Linux kernel, the following vulnerability has been resolved:

btrfs: clean up our handling of refs == 0 in snapshot delete

In reada we BUG_ON(refs == 0), which could be unkind since we aren't
holding a lock on the extent leaf and thus could get a transient
incorrect answer.  In walk_down_proc we also BUG_ON(refs == 0), which
could happen if we have extent tree corruption.  Change that to return
-EUCLEAN.  In do_walk_down() we catch this case and handle it correctly,
however we return -EIO, which -EUCLEAN is a more appropriate error code.
Finally in walk_up_proc we have the same BUG_ON(refs == 0), so convert
that to proper error handling.  Also adjust the error message so we can
actually do something with the information.
Comment 1 Robb Gatica 2024-09-27 14:57:25 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024092754-CVE-2024-46840-fc44@gregkh/T