e2fsck: do not read EA header beyond the end of an inode

In check_inode_extra_space(), if we attempt to read an EA header at
the end of the extra space, in a corrupted filesystem it may result in
a read beyond the bounds of the inode. Add a check to prevent this.

Reproduced by running ./test_one --valgrind f_write_ea_toobig_extra_isize.

Signed-off-by: Artemiy Volkov <artemiyv@acm.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index ac3ea4e..66ff69a 100644 (file)
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -382,6 +382,10 @@ static void check_inode_extra_space(e2fsck_t ctx, struct problem_context *pctx)
                return;
        }
 
+       /* check if there is no place for an EA header */
+       if (inode->i_extra_isize >= max - sizeof(__u32))
+               return;
+
        eamagic = (__u32 *) (((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
                        inode->i_extra_isize);
        if (*eamagic == EXT2_EXT_ATTR_MAGIC) {