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

Overview

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

• Linux >= ff750311d30acc9564ef577050794953eee59f01 < b02948a23455f8190a53887b2d2c13ae1d360cea
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < 9d9c5c218ea356a1d88765214ad2919605280ab1
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < 7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < c68e0068a236f9a7dfc19720bdf11e5d80a85089
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < 88c673a0bd233df44ca0020da82f4fd3876de27a
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < 0cb85377daaefb4ce5ce72975f2deb27ee0e0cad
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < e1ca4e3a380ef3e8f46ce006f1146392e3f32c98
• Linux >= ff750311d30acc9564ef577050794953eee59f01 < 1f7745fb3580152ca902ef181b605f33cabfb1d0
• Linux 2.6.39

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.