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Commit 75d6ad38 authored by David Sterba's avatar David Sterba Committed by Chris Mason
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btrfs: more superblock checks, lower bounds on devices and sectorsize/nodesize 



I received a few crafted images from Jiri, all got through the recently
added superblock checks. The lower bounds checks for num_devices and
sector/node -sizes were missing and caused a crash during mount.

Tools for symbolic code execution were used to prepare the images
contents.

Reported-by: default avatarJiri Slaby <jslaby@suse.cz>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.cz>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 9cc97d64

fs/btrfs/disk-io.c

+19 −0
Original line number Diff line number Diff line
@@ -3871,6 +3871,21 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info, 
		printk(KERN_WARNING "BTRFS: log_root block unaligned: %llu\n",

				btrfs_super_log_root(sb));



	/*

	 * Check the lower bound, the alignment and other constraints are

	 * checked later.

	 */

	if (btrfs_super_nodesize(sb) < 4096) {

		printk(KERN_ERR "BTRFS: nodesize too small: %u < 4096\n",

				btrfs_super_nodesize(sb));

		ret = -EINVAL;

	}

	if (btrfs_super_sectorsize(sb) < 4096) {

		printk(KERN_ERR "BTRFS: sectorsize too small: %u < 4096\n",

				btrfs_super_sectorsize(sb));

		ret = -EINVAL;

	}



	if (memcmp(fs_info->fsid, sb->dev_item.fsid, BTRFS_UUID_SIZE) != 0) {

		printk(KERN_ERR "BTRFS: dev_item UUID does not match fsid: %pU != %pU\n",

				fs_info->fsid, sb->dev_item.fsid);
@@ -3884,6 +3899,10 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info, 
	if (btrfs_super_num_devices(sb) > (1UL << 31))

		printk(KERN_WARNING "BTRFS: suspicious number of devices: %llu\n",

				btrfs_super_num_devices(sb));

	if (btrfs_super_num_devices(sb) == 0) {

		printk(KERN_ERR "BTRFS: number of devices is 0\n");

		ret = -EINVAL;

	}



	if (btrfs_super_bytenr(sb) != BTRFS_SUPER_INFO_OFFSET) {

		printk(KERN_ERR "BTRFS: super offset mismatch %llu != %u\n",