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Fix oopses in the CFQ disk scheduler (rhbz#577968)

This commit is contained in:
Chuck Ebbert 2011-06-24 17:02:32 -04:00
parent 1d95757421
commit d111c750cc
2 changed files with 48 additions and 0 deletions
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44
cfq-iosched-fix-locking-around-ioc-ioc-data-assignment.patch Normal file
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@ -0,0 +1,44 @@
From: Jens Axboe <jaxboe@fusionio.com>
Date: Sun, 5 Jun 2011 04:01:13 +0000 (+0200)
Subject: cfq-iosched: fix locking around ioc->ioc_data assignment
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=ab4bd22d3cce6977dc039664cc2d052e3147d662
cfq-iosched: fix locking around ioc->ioc_data assignment
Since we are modifying this RCU pointer, we need to hold
the lock protecting it around it.
This fixes a potential reuse and double free of a cfq
io_context structure. The bug has been in CFQ for a long
time, it hit very few people but those it did hit seemed
to see it a lot.
Tracked in RH bugzilla here:
https://bugzilla.redhat.com/show_bug.cgi?id=577968
Credit goes to Paul Bolle for figuring out that the issue
was around the one-hit ioc->ioc_data cache. Thanks to his
hard work the issue is now fixed.
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3c7b537..545b8d4 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2772,8 +2772,11 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
smp_wmb();
cic->key = cfqd_dead_key(cfqd);
- if (ioc->ioc_data == cic)
+ if (rcu_dereference(ioc->ioc_data) == cic) {
+ spin_lock(&ioc->lock);
rcu_assign_pointer(ioc->ioc_data, NULL);
+ spin_unlock(&ioc->lock);
+ }
if (cic->cfqq[BLK_RW_ASYNC]) {
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);

4
kernel.spec
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@ -665,6 +665,7 @@ Patch580: linux-2.6-sparc-selinux-mprotect-checks.patch
Patch600: block-queue-refcount.patch
Patch601: block-export-blk_-get-put-_queue.patch
Patch602: block-blkdev_get-should-access-bd_disk-only-after.patch
Patch603: cfq-iosched-fix-locking-around-ioc-ioc-data-assignment.patch
# libata
Patch620: ahci-add-another-pci-id-for-marvell.patch
@ -1298,6 +1299,8 @@ ApplyPatch x86-pci-preserve-existing-pci-bfsort-whitelist-for-dell-systems.patch
ApplyPatch block-queue-refcount.patch
ApplyPatch block-export-blk_-get-put-_queue.patch
ApplyPatch block-blkdev_get-should-access-bd_disk-only-after.patch
# rhbz#577968
ApplyPatch cfq-iosched-fix-locking-around-ioc-ioc-data-assignment.patch
# libata
ApplyPatch ahci-add-another-pci-id-for-marvell.patch
@ -2053,6 +2056,7 @@ fi
- CVE-2011-2183: ksm: race between ksmd and exiting task
- Revert 2.6.38.8 patch that broke magicmouse (rhbz#714381)
- Fix drive detection failure on mvsas (rhbz#705019)
- Fix oopses in the CFQ disk scheduler (rhbz#577968)
* Thu Jun 23 2011 Dave Airlie <airlied@redhat.com> 2.6.38.8-34
- drm-i915-snb-irq-stalls-fix.patch: fix Sandybridge IRQ stalls