From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 23 Jul 2017 04:26:44 +0000 (-0400)
Subject: libext2fs: add stricter checks on the inode size in ext2fs_open2()
X-Git-Tag: v1.43.5~26
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bf445b4e68a053d0b5eaf8da0f61a4c9d13fb5a8;p=thirdparty%2Fe2fsprogs.git

libext2fs: add stricter checks on the inode size in ext2fs_open2()

An inode size larger than the block size can cause userspace programs
to crash.

This problem was found using American Fuzzy Lop.

Reported-by: Adam Buchbinder <abuchbinder@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index 0362b2839..da03bc147 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -121,6 +121,7 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 	blk64_t		group_block, blk;
 	char		*dest, *cp;
 	int		group_zero_adjust = 0;
+	int		inode_size;
 #ifdef WORDS_BIGENDIAN
 	unsigned int	groups_per_block;
 	struct ext2_group_desc *gdp;
@@ -297,7 +298,10 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 		goto cleanup;
 	}
 	fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
-	if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
+	inode_size = EXT2_INODE_SIZE(fs->super);
+	if ((inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
+	    (inode_size > fs->blocksize) ||
+	    (inode_size & (inode_size - 1))) {
 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 		goto cleanup;
 	}