ext4: xattr: fix null pointer deref in ext4_raw_inode()

If ext4_get_inode_loc() fails (e.g. if it returns -EFSCORRUPTED),
iloc.bh will remain set to NULL. Since ext4_xattr_inode_dec_ref_all()
lacks error checking, this will lead to a null pointer dereference
in ext4_raw_inode(), called right after ext4_get_inode_loc().

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: c8e008b60492 ("ext4: ignore xattrs past end")
Cc: stable@kernel.org
Signed-off-by: Karina Yankevich <k.yankevich@omp.ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Message-ID: <20251022093253.3546296-1-k.yankevich@omp.ru>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index ce7253b3f549961fccfa2d73905d6b85bed60e68..2e02efbddaaccae6a39b7e78cb256a6f07d64415 100644 (file)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1174,7 +1174,11 @@ ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
        if (block_csum)
                end = (void *)bh->b_data + bh->b_size;
        else {
-               ext4_get_inode_loc(parent, &iloc);
+               err = ext4_get_inode_loc(parent, &iloc);
+               if (err) {
+                       EXT4_ERROR_INODE(parent, "parent inode loc (error %d)", err);
+                       return;
+               }
                end = (void *)ext4_raw_inode(&iloc) + EXT4_SB(parent->i_sb)->s_inode_size;
        }