From fdb24a820a5832ec4532273282cbd4f22c291a0d Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Tue, 17 Feb 2026 05:09:55 +0000 Subject: [PATCH] Squashfs: check metadata block offset is within range Syzkaller reports a "general protection fault in squashfs_copy_data" This is ultimately caused by a corrupted index look-up table, which produces a negative metadata block offset. This is subsequently passed to squashfs_copy_data (via squashfs_read_metadata) where the negative offset causes an out of bounds access. The fix is to check that the offset is within range in squashfs_read_metadata. This will trap this and other cases. Link: https://lkml.kernel.org/r/20260217050955.138351-1-phillip@squashfs.org.uk Fixes: f400e12656ab ("Squashfs: cache operations") Reported-by: syzbot+a9747fe1c35a5b115d3f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/699234e2.a70a0220.2c38d7.00e2.GAE@google.com/ Signed-off-by: Phillip Lougher Cc: Christian Brauner Cc: Signed-off-by: Andrew Morton --- fs/squashfs/cache.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c index 8e958db5f786..67abd4dff222 100644 --- a/fs/squashfs/cache.c +++ b/fs/squashfs/cache.c @@ -344,6 +344,9 @@ int squashfs_read_metadata(struct super_block *sb, void *buffer, if (unlikely(length < 0)) return -EIO; + if (unlikely(*offset < 0 || *offset >= SQUASHFS_METADATA_SIZE)) + return -EIO; + while (length) { entry = squashfs_cache_get(sb, msblk->block_cache, *block, 0); if (entry->error) {