CVE-2026-97487: jfs: handle set_blocksize failures
In the Linux kernel, the following vulnerability has been resolved:
jfs: handle setblocksize failures
jfs uses bufferheads, which don't handle block size > PAGESIZE well. Without this, mounting we will hit the
BUGON(offset >= foliosize(folio));
in foliosetbh on the first breadgfp call.
Affected Software
Event History
Frequently Asked Questions
What conditions trigger the failure?
The failure occurs when mounting a JFS filesystem whose block size is larger than PAGE_SIZE. JFS uses buffer_heads, which do not handle block sizes greater than PAGE_SIZE correctly, leading to a BUG_ON in folio_set_bh during the first __bread_gfp call.
What is the operational impact?
Attempting to mount an affected JFS filesystem can hit a kernel BUG_ON, interrupting the mount operation and potentially causing a kernel failure.
How can administrators determine whether they are exposed?
Systems are exposed if they mount JFS filesystems with a block size greater than PAGE_SIZE. The relevant condition is encountered during the mount path, specifically on the first __bread_gfp call.