ext4: missing !bh check in ext4_xattr_inode_write()

vaverin · tytso · commit eb6984fa4ce2 · 2018-11-09T11:34:40.000-05:00
According to Ted Ts'o ext4_getblk() called in ext4_xattr_inode_write() should not return bh = NULL The only time that bh could be NULL, then, would be in the case of something really going wrong; a programming error elsewhere (perhaps a wild pointer dereference) or I/O error causing on-disk file system corruption (although that would be highly unlikely given that we had *just* allocated the blocks and so the metadata blocks in question probably would still be in the cache). Fixes: e50e512 ("ext4: xattr-in-inode support") Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org # 4.13
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
@@ -1384,6 +1384,12 @@ static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
 		bh = ext4_getblk(handle, ea_inode, block, 0);
 		if (IS_ERR(bh))
 			return PTR_ERR(bh);
+		if (!bh) {
+			WARN_ON_ONCE(1);
+			EXT4_ERROR_INODE(ea_inode,
+					 "ext4_getblk() return bh = NULL");
+			return -EFSCORRUPTED;
+		}
 		ret = ext4_journal_get_write_access(handle, bh);
 		if (ret)
 			goto out;
