lkml.org 
[lkml]   [2015]   [Apr]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: NULL deref around blkmq in v4.0-rc1–rc7
From
On Thu, Apr 9, 2015 at 2:25 PM, Jens Axboe <axboe@kernel.dk> wrote:
>
> Not sure why it isn't all zeroed, definitely the saner thing to do at init
> time.

So practically speaking, it might well often be zeroed just because
the BIOS may have initialized memory that way (and big multi-page
allocations have probably not gotten re-used).

> And if this is mpt, we recently ran into some list corruption issues due to
> a bug in the driver. It hit on reboot, but it was scan related, so could be
> a boot issue as well.

So one of the earlier emails had this:

Copyright (c) 1999-2008 LSI Corporation
Fusion MPT SAS Host driver 3.04.20
mptbase: ioc0: Initiating bringup
ioc0: LSISAS1068 A0: Capabilities={Initiator}
scsi host0: ioc0: LSISAS1068 A0, FwRev=00000000h, Ports=8, MaxQ=256, IRQ=22
mptsas: ioc0: attaching ssp device: fw_channel 0, fw_id 1, phy 1,
sas_addr 0x1060504030201a0
scsi 0:0:0:0: Direct-Access VBOX HARDDISK 1.0 PQ: 0 ANSI: 5
scsi 0:0:0:0: Attached scsi generic sg0 type 0
mptbase: ioc1: Initiating bringup
ioc1: LSISAS1068 A0: Capabilities={Initiator}
scsi host1: ioc1: LSISAS1068 A0, FwRev=00000000h, Ports=8, MaxQ=256, IRQ=17
mptsas: ioc1: attaching ssp device: fw_channel 0, fw_id 0, phy 0,
sas_addr 0x60504030201a0
scsi 1:0:0:0: Direct-Access VBOX HARDDISK 1.0 PQ: 0 ANSI: 5
scsi 1:0:0:0: Attached scsi generic sg1 type 0

and I'm assuming that that is the backing storage.

And yes, memory corruption sounds like a more likely cause than
anything else. I don't like how the request data wasn't fully
initialized, but the cmd->sense_buffer pointer itself *should* have
been initialized by the ->init_request() call.

So I don't actually expect my patch to really make any difference,
although I do think that code should be looked at.

Linus


\
 
 \ /
  Last update: 2015-04-10 00:01    [W:0.096 / U:11.000 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site