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medium5.5

CVE-2026-23238

In the Linux kernel, the following vulnerability has been resolved: romfs: check sb_set_blocksize() return value romfs_fill_super() ignores the return value of…

Impact

In the Linux kernel, the following vulnerability has been resolved: romfs: check sb_set_blocksize() return value romfs_fill_super() ignores the return value of sb_set_blocksize(), which can fail if the requested block size is incompatible with the block device's configuration. This can be triggered by setting a loop device's block size larger than PAGE_SIZE using ioctl(LOOP_SET_BLOCK_SIZE, 32768), then mounting a romfs filesystem on that device. When sb_set_blocksize(sb, ROMBSIZE) is called with ROMBSIZE=4096 but the device has logical_block_size=32768, bdev_validate_blocksize() fails because the requested size is smaller than the device's logical block size. sb_set_blocksize() returns 0 (failure), but romfs ignores this and continues mounting. The superblock's block size remains at the device's logical block size (32768). Later, when sb_bread() attempts I/O with this oversized block size, it triggers a kernel BUG in folio_set_bh(): kernel BUG at fs/buffer.c:1582! BUG_ON(size > PAGE_SIZE); Fix by checking the return value of sb_set_blocksize() and failing the mount with -EINVAL if it returns 0.

Affected products

VendorProductAffected versions
LinuxLinux Kernel
from 2.6.12.1 before 5.10.251
from 5.11 before 5.15.201
from 5.16 before 6.1.164
from 6.2 before 6.6.127
from 6.7 before 6.12.74
from 6.13 before 6.18.13

Weakness classification

CWE-617

References