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From 67fed15f639763628507a2e704441acabcce4bdd Mon Sep 17 00:00:00 2001
From: Mark Rustad <mark.d.rustad@intel.com>
Date: Thu, 21 Jun 2012 12:23:42 -0700
Subject: [PATCH 17/73] Fix NULL dereferences in scsi_cmd_to_driver
commit 222a806af830fda34ad1f6bc991cd226916de060 upstream.
Avoid crashing if the private_data pointer happens to be NULL. This has
been seen sometimes when a host reset happens, notably when there are
many LUNs:
host3: Assigned Port ID 0c1601
scsi host3: libfc: Host reset succeeded on port (0c1601)
BUG: unable to handle kernel NULL pointer dereference at 0000000000000350
IP: [<ffffffff81352bb8>] scsi_send_eh_cmnd+0x58/0x3a0
<snip>
Process scsi_eh_3 (pid: 4144, threadinfo ffff88030920c000, task ffff880326b160c0)
Stack:
000000010372e6ba 0000000000000282 000027100920dca0 ffffffffa0038ee0
0000000000000000 0000000000030003 ffff88030920dc80 ffff88030920dc80
00000002000e0000 0000000a00004000 ffff8803242f7760 ffff88031326ed80
Call Trace:
[<ffffffff8105b590>] ? lock_timer_base+0x70/0x70
[<ffffffff81352fbe>] scsi_eh_tur+0x3e/0xc0
[<ffffffff81353a36>] scsi_eh_test_devices+0x76/0x170
[<ffffffff81354125>] scsi_eh_host_reset+0x85/0x160
[<ffffffff81354291>] scsi_eh_ready_devs+0x91/0x110
[<ffffffff813543fd>] scsi_unjam_host+0xed/0x1f0
[<ffffffff813546a8>] scsi_error_handler+0x1a8/0x200
[<ffffffff81354500>] ? scsi_unjam_host+0x1f0/0x1f0
[<ffffffff8106ec3e>] kthread+0x9e/0xb0
[<ffffffff81509264>] kernel_thread_helper+0x4/0x10
[<ffffffff8106eba0>] ? kthread_freezable_should_stop+0x70/0x70
[<ffffffff81509260>] ? gs_change+0x13/0x13
Code: 25 28 00 00 00 48 89 45 c8 31 c0 48 8b 87 80 00 00 00 48 8d b5 60 ff ff ff 89 d1 48 89 fb 41 89 d6 4c 89 fa 48 8b 80 b8 00 00 00
<48> 8b 80 50 03 00 00 48 8b 00 48 89 85 38 ff ff ff 48 8b 07 4c
RIP [<ffffffff81352bb8>] scsi_send_eh_cmnd+0x58/0x3a0
RSP <ffff88030920dc50>
CR2: 0000000000000350
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Marcus Dennis <marcusx.e.dennis@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/scsi/scsi.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 2aeb2e9..831db24 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -785,7 +785,13 @@ static void scsi_done(struct scsi_cmnd *cmd)
/* Move this to a header if it becomes more generally useful */
static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
{
- return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
+ struct scsi_driver **sdp;
+
+ sdp = (struct scsi_driver **)cmd->request->rq_disk->private_data;
+ if (!sdp)
+ return NULL;
+
+ return *sdp;
}
/**
--
1.7.7.6
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