CVE-2025-38415
Squashfs: check return result of sb_min_blocksize
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Squashfs: check return result of sb_min_blocksize
In the Linux kernel, the following vulnerability has been resolved: Squashfs: check return result of sb_min_blocksize Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug. Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails. ---- msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize); ---- sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0. As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64. This subsequently causes the UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') This commit adds a check for a 0 return by sb_min_blocksize().
Reserved 2025-04-16 | Published 2025-07-25 | Updated 2025-07-25 | Assigner Linuxgit.kernel.org/...c/db7096ea160e40d78c67fce52e7cc51bde049497
git.kernel.org/...c/549f9e3d7b60d53808c98b9fde49b4f46d0524a5
git.kernel.org/...c/5c51aa862cbeed2f3887f0382a2708956710bd68
git.kernel.org/...c/6abf6b78c6fb112eee495f5636ffcc350dd2ce25
git.kernel.org/...c/4f99357dadbf9c979ad737156ad4c37fadf7c56b
git.kernel.org/...c/0aff95d9bc7fb5400ca8af507429c4b067bdb425
git.kernel.org/...c/295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282
git.kernel.org/...c/734aa85390ea693bb7eaf2240623d41b03705c84
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