[PATCH 4.9 05/86] scsi: qla2xxx: Fix NULL pointer crash due to active timer for ABTS

Greg Kroah-Hartman
2018-03-16T15:22:28Z

From: himanshu.madhani@cavium.com <himanshu.madhani@cavium.com>

commit 1514839b366417934e2f1328edb50ed1e8a719f5 upstream.

This patch fixes NULL pointer crash due to active timer running for abort
IOCB.

>From crash dump analysis it was discoverd that get_next_timer_interrupt()
encountered a corrupted entry on the timer list.

#9 [ffff95e1f6f0fd40] page_fault at ffffffff914fe8f8
[exception RIP: get_next_timer_interrupt+440]
RIP: ffffffff90ea3088 RSP: ffff95e1f6f0fdf0 RFLAGS: 00010013
RAX: ffff95e1f6451028 RBX: 000218e2389e5f40 RCX: 00000001232ad600
RDX: 0000000000000001 RSI: ffff95e1f6f0fdf0 RDI: 0000000001232ad6
RBP: ffff95e1f6f0fe40 R8: ffff95e1f6451188 R9: 0000000000000001
R10: 0000000000000016 R11: 0000000000000016 R12: 00000001232ad5f6
R13: ffff95e1f6450000 R14: ffff95e1f6f0fdf8 R15: ffff95e1f6f0fe10
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018

Looking at the assembly of get_next_timer_interrupt(), address came
from %r8 (ffff95e1f6451188) which is pointing to list_head with single
entry at ffff95e5ff621178.

0xffffffff90ea307a <get_next_timer_interrupt+426>: mov (%r8),%rdx
0xffffffff90ea307d <get_next_timer_interrupt+429>: cmp %r8,%rdx
0xffffffff90ea3080 <get_next_timer_interrupt+432>: je 0xffffffff90ea30a7 <get_next_timer_interrupt+471>
0xffffffff90ea3082 <get_next_timer_interrupt+434>: nopw 0x0(%rax,%rax,1)
0xffffffff90ea3088 <get_next_timer_interrupt+440>: testb $0x1,0x18(%rdx)

crash> rd ffff95e1f6451188 10
ffff95e1f6451188: ffff95e5ff621178 ffff95e5ff621178 x.b.....x.b.....
ffff95e1f6451198: ffff95e1f6451198 ffff95e1f6451198 ..E.......E.....
ffff95e1f64511a8: ffff95e1f64511a8 ffff95e1f64511a8 ..E.......E.....
ffff95e1f64511b8: ffff95e77cf509a0 ffff95e77cf509a0 ...|.......|....
ffff95e1f64511c8: ffff95e1f64511c8 ffff95e1f64511c8 ..E.......E.....

crash> rd ffff95e5ff621178 10
ffff95e5ff621178: 0000000000000001 ffff95e15936aa00 ..........6Y....
ffff95e5ff621188: 0000000000000000 00000000ffffffff ................
ffff95e5ff621198: 00000000000000a0 0000000000000010 ................
ffff95e5ff6211a8: ffff95e5ff621198 000000000000000c ..b.............
ffff95e5ff6211b8: 00000f5800000000 ffff95e751f8d720 ....X... ..Q....

ffff95e5ff621178 belongs to freed mempool object at ffff95e5ff621080.

CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE
ffff95dc7fd74d00 mnt_cache 384 19785 24948 594 16k
SLAB MEMORY NODE TOTAL ALLOCATED FREE
ffffdc5dabfd8800 ffff95e5ff620000 1 42 29 13
FREE / [ALLOCATED]
ffff95e5ff621080 (cpu 6 cache)

Examining the contents of that memory reveals a pointer to a constant string
in the driver, "abort\0", which is set by qla24xx_async_abort_cmd().

crash> rd ffffffffc059277c 20
ffffffffc059277c: 6e490074726f6261 0074707572726574 abort.Interrupt.
ffffffffc059278c: 00676e696c6c6f50 6920726576697244 Polling.Driver i
ffffffffc059279c: 646f6d207325206e 6974736554000a65 n %s mode..Testi
ffffffffc05927ac: 636976656420676e 786c252074612065 ng device at %lx
ffffffffc05927bc: 6b63656843000a2e 646f727020676e69 ...Checking prod
ffffffffc05927cc: 6f20444920746375 0a2e706968632066 uct ID of chip..
ffffffffc05927dc: 5120646e756f4600 204130303232414c .Found QLA2200A
ffffffffc05927ec: 43000a2e70696843 20676e696b636568 Chip...Checking
ffffffffc05927fc: 65786f626c69616d 6c636e69000a2e73 mailboxes...incl
ffffffffc059280c: 756e696c2f656475 616d2d616d642f78 ude/linux/dma-ma

crash> struct -ox srb_iocb
struct srb_iocb {
union {
struct {...} logio;
struct {...} els_logo;
struct {...} tmf;
struct {...} fxiocb;
struct {...} abt;
struct ct_arg ctarg;
struct {...} mbx;
struct {...} nack;
[0x0 ] } u;
[0xb8] struct timer_list timer;
[0x108] void (*timeout)(void *);
}
SIZE: 0x110

crash> ! bc
ibase=16
obase=10
B8+40
F8

The object is a srb_t, and at offset 0xf8 within that structure
(i.e. ffff95e5ff621080 + f8 -> ffff95e5ff621178) is a struct timer_list.

Cc: <stable@vger.kernel.org> #4.4+
Fixes: 4440e46d5db7 ("[SCSI] qla2xxx: Add IOCB Abort command asynchronous handling.")
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/qla2xxx/qla_init.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -369,6 +369,7 @@ qla24xx_abort_sp_done(void *data, void *
srb_t *sp = (srb_t *)ptr;
struct srb_iocb *abt = &sp->u.iocb_cmd;

+ del_timer(&sp->u.iocb_cmd.timer);
complete(&abt->u.abt.comp);
}