CVE-2026-98636squashfs: Add dictionary size range check to prevent shift-out-of-bounds

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/b02948a23455f8190a53887b2d2c13ae1d360cea
• https://git.kernel.org/stable/c/9d9c5c218ea356a1d88765214ad2919605280ab1
• https://git.kernel.org/stable/c/7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1
• https://git.kernel.org/stable/c/c68e0068a236f9a7dfc19720bdf11e5d80a85089
• https://git.kernel.org/stable/c/88c673a0bd233df44ca0020da82f4fd3876de27a
• https://git.kernel.org/stable/c/0cb85377daaefb4ce5ce72975f2deb27ee0e0cad
• https://git.kernel.org/stable/c/e1ca4e3a380ef3e8f46ce006f1146392e3f32c98
• https://git.kernel.org/stable/c/1f7745fb3580152ca902ef181b605f33cabfb1d0