ext4: check if in-inode xattr is corrupted in ext4_expand_extra_isize_ea()

We aren't checking to see if the in-inode extended attribute is
corrupted before we try to expand the inode's extra isize fields.

This can lead to potential crashes caused by the BUG_ON() check in
ext4_xattr_shift_entries().

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 0441e055c8e8b734a86a31b2f2afcac1d43a013b..e79bd32b9b798735f312ba87e3658e0796c44a2a 100644 (file)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -230,6 +230,27 @@ ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
        return error;
 }
 
+static int
+__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
+                        void *end, const char *function, unsigned int line)
+{
+       struct ext4_xattr_entry *entry = IFIRST(header);
+       int error = -EFSCORRUPTED;
+
+       if (((void *) header >= end) ||
+           (header->h_magic != le32_to_cpu(EXT4_XATTR_MAGIC)))
+               goto errout;
+       error = ext4_xattr_check_names(entry, end, entry);
+errout:
+       if (error)
+               __ext4_error_inode(inode, function, line, 0,
+                                  "corrupted in-inode xattr");
+       return error;
+}
+
+#define xattr_check_inode(inode, header, end) \
+       __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
+
 static inline int
 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 {
@@ -341,7 +362,7 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
        header = IHDR(inode, raw_inode);
        entry = IFIRST(header);
        end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
-       error = ext4_xattr_check_names(entry, end, entry);
+       error = xattr_check_inode(inode, header, end);
        if (error)
                goto cleanup;
        error = ext4_xattr_find_entry(&entry, name_index, name,
@@ -477,7 +498,7 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
        raw_inode = ext4_raw_inode(&iloc);
        header = IHDR(inode, raw_inode);
        end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
-       error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
+       error = xattr_check_inode(inode, header, end);
        if (error)
                goto cleanup;
        error = ext4_xattr_list_entries(dentry, IFIRST(header),
@@ -1040,8 +1061,7 @@ int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
        is->s.here = is->s.first;
        is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
        if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
-               error = ext4_xattr_check_names(IFIRST(header), is->s.end,
-                                              IFIRST(header));
+               error = xattr_check_inode(inode, header, is->s.end);
                if (error)
                        return error;
                /* Find the named attribute. */
@@ -1356,6 +1376,10 @@ retry:
        last = entry;
        total_ino = sizeof(struct ext4_xattr_ibody_header);
 
+       error = xattr_check_inode(inode, header, end);
+       if (error)
+               goto cleanup;
+
        free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
        if (free >= new_extra_isize) {
                entry = IFIRST(header);