CVE-2026-98636

In the Linux kernel, the following vulnerability has been resolved:

squashfs: Add dictionary size range check to prevent shift-out-of-bounds

When an abnormal SquashFS image (COMP_OPTS flag is 1 but dictionary size

is 0) is mounted, and performs shift operations using dictionarysize, the

shift exponent is -1, causing a shift-out-of-bounds.

Detail as below:

squashfs_comp_opts(msblk, buffer, length)

squashfs_xz_comp_opts()

if (comp_opts)

n = ffs(opts->dict_size) - 1;<----opts->dict_size=0, n=-1

if (opts->dict_size != (1 << n) && opts->dict_size !=

(1 << n) + (1 << (n + 1))) <----shift-out-of-bounds

Fix it by adding a dictionary size range check before the shift operation.