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| author |  Theodore Ts'o <tytso@mit.edu>
| 2016-07-05 20:01:52 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu>
| 2016-07-05 20:01:52 -0400 |
| commit | 5b9554dc5bf008ae7f68a52e3d7e76c0920938a2 (patch) | |
| tree | 0e77ba0fce0b9b68920ae7f7d1561ffcb690ba04 /fs/ext4/super.c | |
| parent | ext4: remove unused page_idx (diff) | |
| download | linux-5b9554dc5bf008ae7f68a52e3d7e76c0920938a2.tar.gz linux-5b9554dc5bf008ae7f68a52e3d7e76c0920938a2.tar.bz2 linux-5b9554dc5bf008ae7f68a52e3d7e76c0920938a2.zip | |
ext4: validate s_reserved_gdt_blocks on mount
If s_reserved_gdt_blocks is extremely large, it's possible for
ext4_init_block_bitmap(), which is called when ext4 sets up an
uninitialized block bitmap, to corrupt random kernel memory. Add the
same checks which e2fsck has --- it must never be larger than
blocksize / sizeof(__u32) --- and then add a backup check in
ext4_init_block_bitmap() in case the superblock gets modified after
the file system is mounted.
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/super.c')
| -rw-r--r-- | fs/ext4/super.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 5664ee66b301..13c49af7a06a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3416,6 +3416,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) goto failed_mount; } + if (le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) > (blocksize / 4)) { + ext4_msg(sb, KERN_ERR, + "Number of reserved GDT blocks insanely large: %d", + le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks)); + goto failed_mount; + } + if (sbi->s_mount_opt & EXT4_MOUNT_DAX) { err = bdev_dax_supported(sb, blocksize); if (err) |