Patch "dm raid: fix NULL pointer dereference for raid1 without bitmap" has been added to the 4.9-stable tree
Subsystems (2)
This is a note to let you know that I've just added the patch titled
dm raid: fix NULL pointer dereference for raid1 without bitmap
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-raid-fix-null-pointer-dereference-for-raid1-without-bitmap.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
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7a0c5c5b834fb60764b494b0e39c239da3b0774bMon Sep 17 00:00:00 2001
From: Dmitry Bilunov <[email protected]>
Date: Thu, 30 Mar 2017 18:14:26 +0300
Subject: dm raid: fix NULL pointer dereference for raid1 without bitmap
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From: Dmitry Bilunov <[email protected]>
commit 7a0c5c5b834fb60764b494b0e39c239da3b0774b upstream.
Commit 4257e08 ("dm raid: support to change bitmap region size") introduced a bitmap resize call during preresume phase. User can create a DM device with "raid" target configured as raid1 with no metadata devices to hold superblock/bitmap info. It can be achieved using the following sequence:
truncate -s 32M /dev/shm/raid-test LOOP=$(losetup --show -f /dev/shm/raid-test) dmsetup create raid-test-linear0 --table "0 1024 linear $LOOP 0" dmsetup create raid-test-linear1 --table "0 1024 linear $LOOP 1024" dmsetup create raid-test --table "0 1024 raid raid1 1 2048 2 - /dev/mapper/raid-test-linear0 - /dev/mapper/raid-test-linear1"
This results in the following crash:
[ 4029.110216] device-mapper: raid: Ignoring chunk size parameter for RAID 1 [ 4029.110217] device-mapper: raid: Choosing default region size of 4MiB [ 4029.111349] md/raid1:mdX: active with 2 out of 2 mirrors [ 4029.114770] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 [ 4029.114802] IP: bitmap_resize+0x25/0x7c0 [md_mod] [ 4029.114816] PGD 0 … [ 4029.115059] Hardware name: Aquarius Pro P30 S85 BUY-866/B85M-E, BIOS 2304 05/25/2015 [ 4029.115079] task: ffff88015cc29a80 task.stack: ffffc90001a5c000 [ 4029.115097] RIP: 0010:bitmap_resize+0x25/0x7c0 [md_mod] [ 4029.115112] RSP: 0018:ffffc90001a5fb68 EFLAGS: 00010246 [ 4029.115127] RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000000 [ 4029.115146] RDX: 0000000000000000 RSI: 0000000000000400 RDI: 0000000000000000 [ 4029.115166] RBP: ffffc90001a5fc28 R08: 0000000800000000 R09: 00000008ffffffff [ 4029.115185] R10: ffffea0005661600 R11: ffff88015cc29a80 R12: ffff88021231f058 [ 4029.115204] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 4029.115223] FS: 00007fe73a6b4740(0000) GS:ffff88021ea80000(0000) knlGS:0000000000000000 [ 4029.115245] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 4029.115261] CR2: 0000000000000030 CR3: 0000000159a74000 CR4: 00000000001426e0 [ 4029.115281] Call Trace: [ 4029.115291] ? raid_iterate_devices+0x63/0x80 [dm_raid] [ 4029.115309] ? dm_table_all_devices_attribute.isra.23+0x41/0x70 [dm_mod] [ 4029.115329] ? dm_table_set_restrictions+0x225/0x2d0 [dm_mod] [ 4029.115346] raid_preresume+0x81/0x2e0 [dm_raid] [ 4029.115361] dm_table_resume_targets+0x47/0xe0 [dm_mod] [ 4029.115378] dm_resume+0xa8/0xd0 [dm_mod] [ 4029.115391] dev_suspend+0x123/0x250 [dm_mod] [ 4029.115405] ? table_load+0x350/0x350 [dm_mod] [ 4029.115419] ctl_ioctl+0x1c2/0x490 [dm_mod] [ 4029.115433] dm_ctl_ioctl+0xe/0x20 [dm_mod] [ 4029.115447] do_vfs_ioctl+0x8d/0x5a0 [ 4029.115459] ? ____fput+0x9/0x10 [ 4029.115470] ? task_work_run+0x79/0xa0 [ 4029.115481] SyS_ioctl+0x3c/0x70 [ 4029.115493] entry_SYSCALL_64_fastpath+0x13/0x94
The raid_preresume() function incorrectly assumes that the raid_set has a bitmap enabled if RT_FLAG_RS_BITMAP_LOADED is set. But RT_FLAG_RS_BITMAP_LOADED is getting set in __load_dirty_region_bitmap() even if there is no bitmap present (and bitmap_load() happily returns 0 even if a bitmap isn't present). So the only way forward in the near-term is to check if the bitmap is present by seeing if mddev->bitmap is not NULL after bitmap_load() has been called.
By doing so the above NULL pointer is avoided.
--- drivers/md/dm-raid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/md/dm-raid.c +1 -1
@@ -3589,7 +3589,7 @@ static int raid_preresume(struct dm_targreturn r;/* Resize bitmap to adjust to changed region size (aka MD bitmap chunksize) */ -if (test_bit (RT_FLAG_RS_BITMAP_LOADED , &rs->runtime_flags) && +if (test_bit (RT_FLAG_RS_BITMAP_LOADED , &rs->runtime_flags) && mddev->bitmap && mddev->bitmap_info.chunksize !=to_bytes (rs->requested_bitmap_chunk_sectors)) { r =bitmap_resize (mddev->bitmap, mddev->dev_sectors,to_bytes (rs->requested_bitmap_chunk_sectors),0 );
Patches currently in stable-queue which might be from [email protected] are
queue-4.9/dm-raid-fix-null-pointer-dereference-for-raid1-without-bitmap.patch