diff mbox

xen-blkfront: use a right index when checking requests

Message ID 20170809223140.14298-1-kamatam@amazon.com (mailing list archive)
State New, archived
Headers show

Commit Message

Munehisa Kamata Aug. 9, 2017, 10:31 p.m. UTC 
Since commit d05d7f40791c ("Merge branch 'for-4.8/core' of
git://git.kernel.dk/linux-block") and 3fc9d690936f ("Merge branch
'for-4.8/drivers' of git://git.kernel.dk/linux-block"), blkfront_resume()
has been using an index for iterating ring_info to check request when
iterating blk_shadow in an inner loop. This seems to have been
accidentally introduced during the massive rewrite of the block layer
macros in the commits.

This may cause crash like this:

[11798.057074] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
[11798.058832] IP: [<ffffffff814411fa>] blkfront_resume+0x10a/0x610
....
[11798.061063] Call Trace:
[11798.061063]  [<ffffffff8139ce93>] xenbus_dev_resume+0x53/0x140
[11798.061063]  [<ffffffff8139ce40>] ? xenbus_dev_probe+0x150/0x150
[11798.061063]  [<ffffffff813f359e>] dpm_run_callback+0x3e/0x110
[11798.061063]  [<ffffffff813f3a08>] device_resume+0x88/0x190
[11798.061063]  [<ffffffff813f4cc0>] dpm_resume+0x100/0x2d0
[11798.061063]  [<ffffffff813f5221>] dpm_resume_end+0x11/0x20
[11798.061063]  [<ffffffff813950a8>] do_suspend+0xe8/0x1a0
[11798.061063]  [<ffffffff813954bd>] shutdown_handler+0xfd/0x130
[11798.061063]  [<ffffffff8139aba0>] ? split+0x110/0x110
[11798.061063]  [<ffffffff8139ac26>] xenwatch_thread+0x86/0x120
[11798.061063]  [<ffffffff810b4570>] ? prepare_to_wait_event+0x110/0x110
[11798.061063]  [<ffffffff8108fe57>] kthread+0xd7/0xf0
[11798.061063]  [<ffffffff811da811>] ? kfree+0x121/0x170
[11798.061063]  [<ffffffff8108fd80>] ? kthread_park+0x60/0x60
[11798.061063]  [<ffffffff810863b0>] ?  call_usermodehelper_exec_work+0xb0/0xb0
[11798.061063]  [<ffffffff810864ea>] ?  call_usermodehelper_exec_async+0x13a/0x140
[11798.061063]  [<ffffffff81534a45>] ret_from_fork+0x25/0x30

Use the right index in the inner loop.

Fixes: d05d7f40791c ("Merge branch 'for-4.8/core' of git://git.kernel.dk/linux-block")
Fixes: 3fc9d690936f ("Merge branch 'for-4.8/drivers' of git://git.kernel.dk/linux-block")
Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Reviewed-by: Thomas Friebel <friebelt@amazon.de>
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Roger Pau Monne <roger.pau@citrix.com>
Cc: xen-devel@lists.xenproject.org
Cc: stable@vger.kernel.org
---
 drivers/block/xen-blkfront.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Boris Ostrovsky Aug. 10, 2017, 1:23 a.m. UTC | #1 
On 08/09/2017 06:31 PM, Munehisa Kamata wrote:
> Since commit d05d7f40791c ("Merge branch 'for-4.8/core' of
> git://git.kernel.dk/linux-block") and 3fc9d690936f ("Merge branch
> 'for-4.8/drivers' of git://git.kernel.dk/linux-block"), blkfront_resume()
> has been using an index for iterating ring_info to check request when
> iterating blk_shadow in an inner loop. This seems to have been
> accidentally introduced during the massive rewrite of the block layer
> macros in the commits.
> 
> This may cause crash like this:
> 
> [11798.057074] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
> [11798.058832] IP: [<ffffffff814411fa>] blkfront_resume+0x10a/0x610
> ....
> [11798.061063] Call Trace:
> [11798.061063]  [<ffffffff8139ce93>] xenbus_dev_resume+0x53/0x140
> [11798.061063]  [<ffffffff8139ce40>] ? xenbus_dev_probe+0x150/0x150
> [11798.061063]  [<ffffffff813f359e>] dpm_run_callback+0x3e/0x110
> [11798.061063]  [<ffffffff813f3a08>] device_resume+0x88/0x190
> [11798.061063]  [<ffffffff813f4cc0>] dpm_resume+0x100/0x2d0
> [11798.061063]  [<ffffffff813f5221>] dpm_resume_end+0x11/0x20
> [11798.061063]  [<ffffffff813950a8>] do_suspend+0xe8/0x1a0
> [11798.061063]  [<ffffffff813954bd>] shutdown_handler+0xfd/0x130
> [11798.061063]  [<ffffffff8139aba0>] ? split+0x110/0x110
> [11798.061063]  [<ffffffff8139ac26>] xenwatch_thread+0x86/0x120
> [11798.061063]  [<ffffffff810b4570>] ? prepare_to_wait_event+0x110/0x110
> [11798.061063]  [<ffffffff8108fe57>] kthread+0xd7/0xf0
> [11798.061063]  [<ffffffff811da811>] ? kfree+0x121/0x170
> [11798.061063]  [<ffffffff8108fd80>] ? kthread_park+0x60/0x60
> [11798.061063]  [<ffffffff810863b0>] ?  call_usermodehelper_exec_work+0xb0/0xb0
> [11798.061063]  [<ffffffff810864ea>] ?  call_usermodehelper_exec_async+0x13a/0x140
> [11798.061063]  [<ffffffff81534a45>] ret_from_fork+0x25/0x30
> 
> Use the right index in the inner loop.
> 
> Fixes: d05d7f40791c ("Merge branch 'for-4.8/core' of git://git.kernel.dk/linux-block")
> Fixes: 3fc9d690936f ("Merge branch 'for-4.8/drivers' of git://git.kernel.dk/linux-block")
> Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
> Reviewed-by: Thomas Friebel <friebelt@amazon.de>
> Reviewed-by: Eduardo Valentin <eduval@amazon.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Roger Pau Monne <roger.pau@citrix.com>
> Cc: xen-devel@lists.xenproject.org
> Cc: stable@vger.kernel.org


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Roger Pau Monné Aug. 10, 2017, 9:43 a.m. UTC | #2 
On Wed, Aug 09, 2017 at 03:31:40PM -0700, Munehisa Kamata wrote:
> Since commit d05d7f40791c ("Merge branch 'for-4.8/core' of
> git://git.kernel.dk/linux-block") and 3fc9d690936f ("Merge branch
> 'for-4.8/drivers' of git://git.kernel.dk/linux-block"), blkfront_resume()
> has been using an index for iterating ring_info to check request when
> iterating blk_shadow in an inner loop. This seems to have been
> accidentally introduced during the massive rewrite of the block layer
> macros in the commits.
> 
> This may cause crash like this:
> 
> [11798.057074] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
> [11798.058832] IP: [<ffffffff814411fa>] blkfront_resume+0x10a/0x610
> ....
> [11798.061063] Call Trace:
> [11798.061063]  [<ffffffff8139ce93>] xenbus_dev_resume+0x53/0x140
> [11798.061063]  [<ffffffff8139ce40>] ? xenbus_dev_probe+0x150/0x150
> [11798.061063]  [<ffffffff813f359e>] dpm_run_callback+0x3e/0x110
> [11798.061063]  [<ffffffff813f3a08>] device_resume+0x88/0x190
> [11798.061063]  [<ffffffff813f4cc0>] dpm_resume+0x100/0x2d0
> [11798.061063]  [<ffffffff813f5221>] dpm_resume_end+0x11/0x20
> [11798.061063]  [<ffffffff813950a8>] do_suspend+0xe8/0x1a0
> [11798.061063]  [<ffffffff813954bd>] shutdown_handler+0xfd/0x130
> [11798.061063]  [<ffffffff8139aba0>] ? split+0x110/0x110
> [11798.061063]  [<ffffffff8139ac26>] xenwatch_thread+0x86/0x120
> [11798.061063]  [<ffffffff810b4570>] ? prepare_to_wait_event+0x110/0x110
> [11798.061063]  [<ffffffff8108fe57>] kthread+0xd7/0xf0
> [11798.061063]  [<ffffffff811da811>] ? kfree+0x121/0x170
> [11798.061063]  [<ffffffff8108fd80>] ? kthread_park+0x60/0x60
> [11798.061063]  [<ffffffff810863b0>] ?  call_usermodehelper_exec_work+0xb0/0xb0
> [11798.061063]  [<ffffffff810864ea>] ?  call_usermodehelper_exec_async+0x13a/0x140
> [11798.061063]  [<ffffffff81534a45>] ret_from_fork+0x25/0x30
> 
> Use the right index in the inner loop.
> 
> Fixes: d05d7f40791c ("Merge branch 'for-4.8/core' of git://git.kernel.dk/linux-block")
> Fixes: 3fc9d690936f ("Merge branch 'for-4.8/drivers' of git://git.kernel.dk/linux-block")
> Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
> Reviewed-by: Thomas Friebel <friebelt@amazon.de>
> Reviewed-by: Eduardo Valentin <eduval@amazon.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Roger Pau Monne <roger.pau@citrix.com>
> Cc: xen-devel@lists.xenproject.org
> Cc: stable@vger.kernel.org

Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks, Roger.
diff mbox

Patch

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 98e34e4c62b8..2468c28d4771 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2075,9 +2075,9 @@  static int blkfront_resume(struct xenbus_device *dev)
 			/*
 			 * Get the bios in the request so we can re-queue them.
 			 */
-			if (req_op(shadow[i].request) == REQ_OP_FLUSH ||
-			    req_op(shadow[i].request) == REQ_OP_DISCARD ||
-			    req_op(shadow[i].request) == REQ_OP_SECURE_ERASE ||
+			if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
+			    req_op(shadow[j].request) == REQ_OP_DISCARD ||
+			    req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
 			    shadow[j].request->cmd_flags & REQ_FUA) {
 				/*
 				 * Flush operations don't contain bios, so