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authorTakahiro Yasui <tyasui@redhat.com>2010-02-16 18:42:58 +0000
committerAlasdair G Kergon <agk@redhat.com>2010-02-16 18:42:58 +0000
commit558569aa9d83e016295bac77d900342908d7fd85 (patch)
treefb8f887855462b23629c9955229ac714cbf77d0d
parent5528d17de1cf1462f285c40ccaf8e0d0e4c64dc0 (diff)
downloadop-kernel-dev-558569aa9d83e016295bac77d900342908d7fd85.zip
op-kernel-dev-558569aa9d83e016295bac77d900342908d7fd85.tar.gz
dm raid1: fix null pointer dereference in suspend
When suspending a failed mirror, bios are completed by mirror_end_io() and __rh_lookup() in dm_rh_dec() returns NULL where a non-NULL return value is required by design. Fix this by not changing the state of the recovery failed region from DM_RH_RECOVERING to DM_RH_NOSYNC in dm_rh_recovery_end(). Issue On 2.6.33-rc1 kernel, I hit the bug when I suspended the failed mirror by dmsetup command. BUG: unable to handle kernel NULL pointer dereference at 00000020 IP: [<f94f38e2>] dm_rh_dec+0x35/0xa1 [dm_region_hash] ... EIP: 0060:[<f94f38e2>] EFLAGS: 00010046 CPU: 0 EIP is at dm_rh_dec+0x35/0xa1 [dm_region_hash] EAX: 00000286 EBX: 00000000 ECX: 00000286 EDX: 00000000 ESI: eff79eac EDI: eff79e80 EBP: f6915cd4 ESP: f6915cc4 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 Process dmsetup (pid: 2849, ti=f6914000 task=eff03e80 task.ti=f6914000) ... Call Trace: [<f9530af6>] ? mirror_end_io+0x53/0x1b1 [dm_mirror] [<f9413104>] ? clone_endio+0x4d/0xa2 [dm_mod] [<f9530aa3>] ? mirror_end_io+0x0/0x1b1 [dm_mirror] [<f94130b7>] ? clone_endio+0x0/0xa2 [dm_mod] [<c02d6bcb>] ? bio_endio+0x28/0x2b [<f952f303>] ? hold_bio+0x2d/0x62 [dm_mirror] [<f952f942>] ? mirror_presuspend+0xeb/0xf7 [dm_mirror] [<c02aa3e2>] ? vmap_page_range+0xb/0xd [<f9414c8d>] ? suspend_targets+0x2d/0x3b [dm_mod] [<f9414ca9>] ? dm_table_presuspend_targets+0xe/0x10 [dm_mod] [<f941456f>] ? dm_suspend+0x4d/0x150 [dm_mod] [<f941767d>] ? dev_suspend+0x55/0x18a [dm_mod] [<c0343762>] ? _copy_from_user+0x42/0x56 [<f9417fb0>] ? dm_ctl_ioctl+0x22c/0x281 [dm_mod] [<f9417628>] ? dev_suspend+0x0/0x18a [dm_mod] [<f9417d84>] ? dm_ctl_ioctl+0x0/0x281 [dm_mod] [<c02c3c4b>] ? vfs_ioctl+0x22/0x85 [<c02c422c>] ? do_vfs_ioctl+0x4cb/0x516 [<c02c42b7>] ? sys_ioctl+0x40/0x5a [<c0202858>] ? sysenter_do_call+0x12/0x28 Analysis When recovery process of a region failed, dm_rh_recovery_end() function changes the state of the region from RM_RH_RECOVERING to DM_RH_NOSYNC. When recovery_complete() is executed between dm_rh_update_states() and dm_writes() in do_mirror(), bios are processed with the region state, DM_RH_NOSYNC. However, the region data is freed without checking its pending count when dm_rh_update_states() is called next time. When bios are finished by mirror_end_io(), __rh_lookup() in dm_rh_dec() returns NULL even though a valid return value are expected. Solution Remove the state change of the recovery failed region from DM_RH_RECOVERING to DM_RH_NOSYNC in dm_rh_recovery_end(). We can remove the state change because: - If the region data has been released by dm_rh_update_states(), a new region data is created with the state of DM_RH_NOSYNC, and bios are processed according to the DM_RH_NOSYNC state. - If the region data has not been released by dm_rh_update_states(), a state of the region is DM_RH_RECOVERING and bios are put in the delayed_bio list. The flag change from DM_RH_RECOVERING to DM_RH_NOSYNC in dm_rh_recovery_end() was added in the following commit: dm raid1: handle resync failures author Jonathan Brassow <jbrassow@redhat.com> Thu, 12 Jul 2007 16:29:04 +0000 (17:29 +0100) http://git.kernel.org/linus/f44db678edcc6f4c2779ac43f63f0b9dfa28b724 Signed-off-by: Takahiro Yasui <tyasui@redhat.com> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-region-hash.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
index 5f19ceb..168bd38 100644
--- a/drivers/md/dm-region-hash.c
+++ b/drivers/md/dm-region-hash.c
@@ -660,10 +660,9 @@ void dm_rh_recovery_end(struct dm_region *reg, int success)
spin_lock_irq(&rh->region_lock);
if (success)
list_add(&reg->list, &reg->rh->recovered_regions);
- else {
- reg->state = DM_RH_NOSYNC;
+ else
list_add(&reg->list, &reg->rh->failed_recovered_regions);
- }
+
spin_unlock_irq(&rh->region_lock);
rh->wakeup_workers(rh->context);
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