diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2016-07-05 20:01:52 -0400 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-12-31 01:44:58 +0100 |
| commit | b7e52c7a982fe106c039f54907443b926c7f224c (patch) | |
| tree | f177973baef8ac4a7d1745880720ec50b16b1387 /fs | |
| parent | cbe7359580f5f9007a3b5690b5794795a117049d (diff) | |
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
[@nathanchance: fixed conflicts]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Joe Maples <joe@frap129.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/balloc.c | 3 | ||||
| -rw-r--r-- | fs/ext4/super.c | 7 |
2 files changed, 10 insertions, 0 deletions
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index 83a6f497c..e1d4495ac 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -209,6 +209,9 @@ static int ext4_init_block_bitmap(struct super_block *sb, memset(bh->b_data, 0, sb->s_blocksize); bit_max = ext4_num_base_meta_clusters(sb, block_group); + if ((bit_max >> 3) >= bh->b_size) + return -EFSCORRUPTED; + for (bit = 0; bit < bit_max; bit++) ext4_set_bit(bit, bh->b_data); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 5f9db470d..c1d91e575 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3403,6 +3403,13 @@ 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 (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_ENCRYPT) && es->s_encryption_level) { ext4_msg(sb, KERN_ERR, "Unsupported encryption level %d", |