]> www.infradead.org Git - users/jedix/linux-maple.git/commit
blk-mq: fix buffer overflow when reading sysfs file of 'pending'
authorMing Lei <ming.lei@canonical.com>
Sun, 9 Aug 2015 07:41:50 +0000 (03:41 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 29 Sep 2015 17:25:56 +0000 (19:25 +0200)
commit1af97771b397a9ca2ee984c3277bcada3eec95cd
tree9c4a0c47cbc0af1ba792c8039b85a057b851236c
parent4fbdb442390e3eeb755d299c3dcbc777ea83f193
blk-mq: fix buffer overflow when reading sysfs file of 'pending'

commit 596f5aad2a704b72934e5abec1b1b4114c16f45b upstream.

There may be lots of pending requests so that the buffer of PAGE_SIZE
can't hold them at all.

One typical example is scsi-mq, the queue depth(.can_queue) of
scsi_host and blk-mq is quite big but scsi_device's queue_depth
is a bit small(.cmd_per_lun), then it is quite easy to have lots
of pending requests in hw queue.

This patch fixes the following warning and the related memory
destruction.

[  359.025101] fill_read_buffer: blk_mq_hw_sysfs_show+0x0/0x7d returned bad count^M
[  359.055595] irq event stamp: 15537^M
[  359.055606] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M
[  359.055614] Dumping ftrace buffer:^M
[  359.055660]    (ftrace buffer empty)^M
[  359.055672] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M
[  359.055678] CPU: 4 PID: 21631 Comm: stress-ng-sysfs Not tainted 4.2.0-rc5-next-20150805 #434^M
[  359.055679] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M
[  359.055682] task: ffff8802161cc000 ti: ffff88021b4a8000 task.ti: ffff88021b4a8000^M
[  359.055693] RIP: 0010:[<ffffffff811541c5>]  [<ffffffff811541c5>] __kmalloc+0xe8/0x152^M

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
block/blk-mq-sysfs.c