* [PATCH] MIPS: cevt-r4k: Fix out-of-bounds array access
@ 2017-04-05 15:32 James Hogan
2017-04-05 15:32 ` James Hogan
2017-04-10 11:31 ` Ralf Baechle
0 siblings, 2 replies; 3+ messages in thread
From: James Hogan @ 2017-04-05 15:32 UTC (permalink / raw)
To: Ralf Baechle; +Cc: Rabin Vincent, linux-mips, stable, James Hogan
calculate_min_delta() may incorrectly access a 4th element of buf2[]
which only has 3 elements. This may trigger undefined behaviour and has
been reported to cause strange crashes in start_kernel() sometime after
timer initialization when built with GCC 5.3, possibly due to
register/stack corruption:
sched_clock: 32 bits at 200MHz, resolution 5ns, wraps every 10737418237ns
CPU 0 Unable to handle kernel paging request at virtual address ffffb0aa, epc == 8067daa8, ra == 8067da84
Oops[#1]:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.18 #51
task: 8065e3e0 task.stack: 80644000
$ 0 : 00000000 00000001 00000000 00000000
$ 4 : 8065b4d0 00000000 805d0000 00000010
$ 8 : 00000010 80321400 fffff000 812de408
$12 : 00000000 00000000 00000000 ffffffff
$16 : 00000002 ffffffff 80660000 806a666c
$20 : 806c0000 00000000 00000000 00000000
$24 : 00000000 00000010
$28 : 80644000 80645ed0 00000000 8067da84
Hi : 00000000
Lo : 00000000
epc : 8067daa8 start_kernel+0x33c/0x500
ra : 8067da84 start_kernel+0x318/0x500
Status: 11000402 KERNEL EXL
Cause : 4080040c (ExcCode 03)
BadVA : ffffb0aa
PrId : 0501992c (MIPS 1004Kc)
Modules linked in:
Process swapper/0 (pid: 0, threadinfo=80644000, task=8065e3e0, tls=00000000)
Call Trace:
[<8067daa8>] start_kernel+0x33c/0x500
Code: 24050240 0c0131f9 24849c64 <a200b0a8> 41606020 000000c0 0c1a45e6 00000000 0c1a5f44
UBSAN also detects the same issue:
================================================================
UBSAN: Undefined behaviour in arch/mips/kernel/cevt-r4k.c:85:41
load of address 80647e4c with insufficient space
for an object of type 'unsigned int'
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.18 #47
Call Trace:
[<80028f70>] show_stack+0x88/0xa4
[<80312654>] dump_stack+0x84/0xc0
[<8034163c>] ubsan_epilogue+0x14/0x50
[<803417d8>] __ubsan_handle_type_mismatch+0x160/0x168
[<8002dab0>] r4k_clockevent_init+0x544/0x764
[<80684d34>] time_init+0x18/0x90
[<8067fa5c>] start_kernel+0x2f0/0x500
=================================================================
buf2[] is intentionally only 3 elements so that the last element is the
median once 5 samples have been inserted, so explicitly prevent the
possibility of comparing against the 4th element rather than extending
the array.
Fixes: 1fa405552e33f2 ("MIPS: cevt-r4k: Dynamically calculate min_delta_ns")
Reported-by: Rabin Vincent <rabinv@axis.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Tested-by: Rabin Vincent <rabinv@axis.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.7.x-
---
arch/mips/kernel/cevt-r4k.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 804d2a2a19fe..dd6a18bc10ab 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -80,7 +80,7 @@ static unsigned int calculate_min_delta(void)
}
/* Sorted insert of 75th percentile into buf2 */
- for (k = 0; k < i; ++k) {
+ for (k = 0; k < i && k < ARRAY_SIZE(buf2); ++k) {
if (buf1[ARRAY_SIZE(buf1) - 1] < buf2[k]) {
l = min_t(unsigned int,
i, ARRAY_SIZE(buf2) - 1);
--
git-series 0.8.10
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH] MIPS: cevt-r4k: Fix out-of-bounds array access
2017-04-05 15:32 [PATCH] MIPS: cevt-r4k: Fix out-of-bounds array access James Hogan
@ 2017-04-05 15:32 ` James Hogan
2017-04-10 11:31 ` Ralf Baechle
1 sibling, 0 replies; 3+ messages in thread
From: James Hogan @ 2017-04-05 15:32 UTC (permalink / raw)
To: Ralf Baechle; +Cc: Rabin Vincent, linux-mips, stable, James Hogan
calculate_min_delta() may incorrectly access a 4th element of buf2[]
which only has 3 elements. This may trigger undefined behaviour and has
been reported to cause strange crashes in start_kernel() sometime after
timer initialization when built with GCC 5.3, possibly due to
register/stack corruption:
sched_clock: 32 bits at 200MHz, resolution 5ns, wraps every 10737418237ns
CPU 0 Unable to handle kernel paging request at virtual address ffffb0aa, epc == 8067daa8, ra == 8067da84
Oops[#1]:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.18 #51
task: 8065e3e0 task.stack: 80644000
$ 0 : 00000000 00000001 00000000 00000000
$ 4 : 8065b4d0 00000000 805d0000 00000010
$ 8 : 00000010 80321400 fffff000 812de408
$12 : 00000000 00000000 00000000 ffffffff
$16 : 00000002 ffffffff 80660000 806a666c
$20 : 806c0000 00000000 00000000 00000000
$24 : 00000000 00000010
$28 : 80644000 80645ed0 00000000 8067da84
Hi : 00000000
Lo : 00000000
epc : 8067daa8 start_kernel+0x33c/0x500
ra : 8067da84 start_kernel+0x318/0x500
Status: 11000402 KERNEL EXL
Cause : 4080040c (ExcCode 03)
BadVA : ffffb0aa
PrId : 0501992c (MIPS 1004Kc)
Modules linked in:
Process swapper/0 (pid: 0, threadinfo=80644000, task=8065e3e0, tls=00000000)
Call Trace:
[<8067daa8>] start_kernel+0x33c/0x500
Code: 24050240 0c0131f9 24849c64 <a200b0a8> 41606020 000000c0 0c1a45e6 00000000 0c1a5f44
UBSAN also detects the same issue:
================================================================
UBSAN: Undefined behaviour in arch/mips/kernel/cevt-r4k.c:85:41
load of address 80647e4c with insufficient space
for an object of type 'unsigned int'
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.18 #47
Call Trace:
[<80028f70>] show_stack+0x88/0xa4
[<80312654>] dump_stack+0x84/0xc0
[<8034163c>] ubsan_epilogue+0x14/0x50
[<803417d8>] __ubsan_handle_type_mismatch+0x160/0x168
[<8002dab0>] r4k_clockevent_init+0x544/0x764
[<80684d34>] time_init+0x18/0x90
[<8067fa5c>] start_kernel+0x2f0/0x500
=================================================================
buf2[] is intentionally only 3 elements so that the last element is the
median once 5 samples have been inserted, so explicitly prevent the
possibility of comparing against the 4th element rather than extending
the array.
Fixes: 1fa405552e33f2 ("MIPS: cevt-r4k: Dynamically calculate min_delta_ns")
Reported-by: Rabin Vincent <rabinv@axis.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Tested-by: Rabin Vincent <rabinv@axis.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.7.x-
---
arch/mips/kernel/cevt-r4k.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 804d2a2a19fe..dd6a18bc10ab 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -80,7 +80,7 @@ static unsigned int calculate_min_delta(void)
}
/* Sorted insert of 75th percentile into buf2 */
- for (k = 0; k < i; ++k) {
+ for (k = 0; k < i && k < ARRAY_SIZE(buf2); ++k) {
if (buf1[ARRAY_SIZE(buf1) - 1] < buf2[k]) {
l = min_t(unsigned int,
i, ARRAY_SIZE(buf2) - 1);
--
git-series 0.8.10
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] MIPS: cevt-r4k: Fix out-of-bounds array access
2017-04-05 15:32 [PATCH] MIPS: cevt-r4k: Fix out-of-bounds array access James Hogan
2017-04-05 15:32 ` James Hogan
@ 2017-04-10 11:31 ` Ralf Baechle
1 sibling, 0 replies; 3+ messages in thread
From: Ralf Baechle @ 2017-04-10 11:31 UTC (permalink / raw)
To: James Hogan; +Cc: Rabin Vincent, linux-mips, stable
On Wed, Apr 05, 2017 at 04:32:45PM +0100, James Hogan wrote:
Thanks, applied.
Ralf
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-04-10 11:31 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2017-04-05 15:32 [PATCH] MIPS: cevt-r4k: Fix out-of-bounds array access James Hogan
2017-04-05 15:32 ` James Hogan
2017-04-10 11:31 ` Ralf Baechle
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