From 43d10880aa4ac713cf73dbac428be9671ef1bf9d Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 30 Nov 2015 17:27:06 +0100 Subject: [PATCH 1/2] btrfs: handle invalid num_stripes in sys_array We can handle the special case of num_stripes == 0 directly inside btrfs_read_sys_array. The BUG_ON in btrfs_chunk_item_size is there to catch other unhandled cases where we fail to validate external data. A crafted or corrupted image crashes at mount time: BTRFS: device fsid 9006933e-2a9a-44f0-917f-514252aeec2c devid 1 transid 7 /dev/loop0 BTRFS info (device loop0): disk space caching is enabled BUG: failure at fs/btrfs/ctree.h:337/btrfs_chunk_item_size()! Kernel panic - not syncing: BUG! CPU: 0 PID: 313 Comm: mount Not tainted 4.2.5-00657-ge047887-dirty #25 Stack: 637af890 60062489 602aeb2e 604192ba 60387961 00000011 637af8a0 6038a835 637af9c0 6038776b 634ef32b 00000000 Call Trace: [<6001c86d>] show_stack+0xfe/0x15b [<6038a835>] dump_stack+0x2a/0x2c [<6038776b>] panic+0x13e/0x2b3 [<6020f099>] btrfs_read_sys_array+0x25d/0x2ff [<601cfbbe>] open_ctree+0x192d/0x27af [<6019c2c1>] btrfs_mount+0x8f5/0xb9a [<600bc9a7>] mount_fs+0x11/0xf3 [<600d5167>] vfs_kern_mount+0x75/0x11a [<6019bcb0>] btrfs_mount+0x2e4/0xb9a [<600bc9a7>] mount_fs+0x11/0xf3 [<600d5167>] vfs_kern_mount+0x75/0x11a [<600d710b>] do_mount+0xa35/0xbc9 [<600d7557>] SyS_mount+0x95/0xc8 [<6001e884>] handle_syscall+0x6b/0x8e Reported-by: Jiri Slaby Reported-by: Vegard Nossum CC: stable@vger.kernel.org # 3.19+ Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6fc735869c18..b816b3a2e118 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -6399,6 +6399,14 @@ int btrfs_read_sys_array(struct btrfs_root *root) goto out_short_read; num_stripes = btrfs_chunk_num_stripes(sb, chunk); + if (!num_stripes) { + printk(KERN_ERR + "BTRFS: invalid number of stripes %u in sys_array at offset %u\n", + num_stripes, cur_offset); + ret = -EIO; + break; + } + len = btrfs_chunk_item_size(num_stripes); if (cur_offset + len > array_size) goto out_short_read; -- 2.5.0