2014-11-11 17:04:22

by Shuah Khan

Subject: [PATCH] selftests/net: psock_fanout seg faults in sock_fanout_read_ring()

The while loop in sock_fanout_read_ring() checks mmap region
bounds after access, causing it to segfault. Fix it to check
count before accessing header->tp_status. This problem can be
reproduced consistently when the test in run as follows:

make -C tools/testing/selftests TARGETS=net run_tests
or
make run_tests from tools/testing/selftests
or
make run_test from tools/testing/selftests/net

Signed-off-by: Shuah Khan <[email protected]>
---
tools/testing/selftests/net/psock_fanout.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/psock_fanout.c b/tools/testing/selftests/net/psock_fanout.c
index 57b9c2b..6f67333 100644
--- a/tools/testing/selftests/net/psock_fanout.c
+++ b/tools/testing/selftests/net/psock_fanout.c
@@ -128,7 +128,7 @@ static int sock_fanout_read_ring(int fd, void *ring)
struct tpacket2_hdr *header = ring;
int count = 0;

- while (header->tp_status & TP_STATUS_USER && count < RING_NUM_FRAMES) {
+ while (count < RING_NUM_FRAMES && header->tp_status & TP_STATUS_USER) {
count++;
header = ring + (count * getpagesize());
}
--
1.9.1

2014-11-12 02:44:10

by David Miller

Subject: Re: [PATCH] selftests/net: psock_fanout seg faults in sock_fanout_read_ring()

From: Shuah Khan <[email protected]>
Date: Tue, 11 Nov 2014 10:04:13 -0700

> The while loop in sock_fanout_read_ring() checks mmap region
> bounds after access, causing it to segfault. Fix it to check
> count before accessing header->tp_status. This problem can be
> reproduced consistently when the test in run as follows:
>
> make -C tools/testing/selftests TARGETS=net run_tests
> or
> make run_tests from tools/testing/selftests
> or
> make run_test from tools/testing/selftests/net
>
> Signed-off-by: Shuah Khan <[email protected]>

Definitely looks correct to me, applied, thanks.