From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120205220952.399096942@pcw.home.local> Date: Sun, 05 Feb 2012 23:10:58 +0100 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Babu Moger , James Bottomley , Dan Carpenter , Greg KH Subject: [PATCH 69/91] SCSI: scsi_dh: check queuedata pointer before proceeding further In-Reply-To: <0635750f5f06ed2ca212b91fcb5c4483@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: 2.6.27-longterm review patch. If anyone has any objections, please let us know. ------------------ commit a18a920c70d48a8e4a2b750d8a183b3c1a4be514 upstream. This patch validates sdev pointer in scsi_dh_activate before proceeding further. Without this check we might see the panic as below. I have seen this panic multiple times.. Call trace: #0 [ffff88007d647b50] machine_kexec at ffffffff81020902 #1 [ffff88007d647ba0] crash_kexec at ffffffff810875b0 #2 [ffff88007d647c70] oops_end at ffffffff8139c650 #3 [ffff88007d647c90] __bad_area_nosemaphore at ffffffff8102dd15 #4 [ffff88007d647d50] page_fault at ffffffff8139b8cf [exception RIP: scsi_dh_activate+0x82] RIP: ffffffffa0041922 RSP: ffff88007d647e00 RFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000000093c5 RDX: 00000000000093c5 RSI: ffffffffa02e6640 RDI: ffff88007cc88988 RBP: 000000000000000f R8: ffff88007d646000 R9: 0000000000000000 R10: ffff880082293790 R11: 00000000ffffffff R12: ffff88007cc88988 R13: 0000000000000000 R14: 0000000000000286 R15: ffff880037b845e0 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0000 #5 [ffff88007d647e38] run_workqueue at ffffffff81060268 #6 [ffff88007d647e78] worker_thread at ffffffff81060386 #7 [ffff88007d647ee8] kthread at ffffffff81064436 #8 [ffff88007d647f48] kernel_thread at ffffffff81003fba Signed-off-by: Babu Moger Signed-off-by: James Bottomley Signed-off-by: Dan Carpenter Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/device_handler/scsi_dh.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-) Index: longterm-2.6.27/drivers/scsi/device_handler/scsi_dh.c =================================================================== --- longterm-2.6.27.orig/drivers/scsi/device_handler/scsi_dh.c 2012-02-05 22:34:32.891915048 +0100 +++ longterm-2.6.27/drivers/scsi/device_handler/scsi_dh.c 2012-02-05 22:34:44.687914590 +0100 @@ -423,7 +423,12 @@ spin_lock_irqsave(q->queue_lock, flags); sdev = q->queuedata; - if (sdev && sdev->scsi_dh_data) + if (!sdev) { + spin_unlock_irqrestore(q->queue_lock, flags); + return SCSI_DH_NOSYS; + } + + if (sdev->scsi_dh_data) scsi_dh = sdev->scsi_dh_data->scsi_dh; if (!scsi_dh || !get_device(&sdev->sdev_gendev)) err = SCSI_DH_NOSYS;