Re: [syzbot] Re: [syzbot] [squashfs?] KMSAN: uninit-value in pick_link

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Subject: Re: [syzbot] [squashfs?] KMSAN: uninit-value in pick_link
Author: lizhi.xu@windriver.com

when i_size in read_inode, check it

#syz test: upstream 2f8c4f506285

diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
index 16bd693d0b3a..8f5d89dc334b 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -273,21 +273,28 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 	case SQUASHFS_SYMLINK_TYPE:
 	case SQUASHFS_LSYMLINK_TYPE: {
 		struct squashfs_symlink_inode *sqsh_ino = &squashfs_ino.symlink;
+		loff_t symlink_size;
 
 		err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 				sizeof(*sqsh_ino));
 		if (err < 0)
 			goto failed_read;
 
+		symlink_size = le32_to_cpu(sqsh_ino->symlink_size);
+		if ((int)symlink_size < 0 || symlink_size > PAGE_SIZE) {
+			ERROR("Corrupted symlink, size [%lld]\n", symlink_size);
+			return -EINVAL;
+		}
+
 		set_nlink(inode, le32_to_cpu(sqsh_ino->nlink));
-		inode->i_size = le32_to_cpu(sqsh_ino->symlink_size);
+		inode->i_size = symlink_size;
 		inode->i_op = &squashfs_symlink_inode_ops;
 		inode_nohighmem(inode);
 		inode->i_data.a_ops = &squashfs_symlink_aops;
 		inode->i_mode |= S_IFLNK;
 		squashfs_i(inode)->start = block;
 		squashfs_i(inode)->offset = offset;
-
+		
 		if (type == SQUASHFS_LSYMLINK_TYPE) {
 			__le32 xattr;
 
-- 
2.43.0