syzbot report KMSAN: uninit-value in pick_link, the root cause is that squashfs_symlink_read_folio did not check the length, resulting in folio not being initialized and did not return the corresponding error code. The length is calculated from i_size, so it is necessary to add a check when i_size is initialized to confirm that its value is correct, otherwise an error -EINVAL will be returned. Strictly, the check only applies to the symlink type. Add larger symlink check. Reported-and-tested-by: syzbot+24ac24ff58dc5b0d26b9@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=24ac24ff58dc5b0d26b9 Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx> --- fs/squashfs/inode.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c index 16bd693d0b3a..6c5dd225482f 100644 --- a/fs/squashfs/inode.c +++ b/fs/squashfs/inode.c @@ -287,6 +287,11 @@ int squashfs_read_inode(struct inode *inode, long long ino) inode->i_mode |= S_IFLNK; squashfs_i(inode)->start = block; squashfs_i(inode)->offset = offset; + if ((int)inode->i_size < 0 || inode->i_size > PAGE_SIZE) { + ERROR("Wrong i_size %d!\n", inode->i_size); + return -EINVAL; + } + if (type == SQUASHFS_LSYMLINK_TYPE) { __le32 xattr; -- 2.43.0
