diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2016-07-05 20:01:52 -0400 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2016-08-22 12:23:04 -0400 |
| commit | 5467159ce7daea9c2f7548b1a7835ee6cecbfb68 (patch) | |
| tree | b6347a4e8d714a1e96060565333919395f6b4b86 /fs | |
| parent | 926d244dfa891826a40d6af950209c3b90868149 (diff) | |
ext4: validate s_reserved_gdt_blocks on mount
[ Upstream commit e1d8c1feecf672379c50ab045fd94548468bc987 ]
[ Upstream commit 5b9554dc5bf008ae7f68a52e3d7e76c0920938a2 ]
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
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
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 83a6f497c4e0..cb3860817fed 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 -EIO; + 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 a5d94f263870..854801795882 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3668,6 +3668,13 @@ 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 (sb->s_blocksize != blocksize) { /* Validate the filesystem blocksize */ if (!sb_set_blocksize(sb, blocksize)) { |