| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <tjuxwbbkwyi2ggjv6744h27rkk3kjhdbkv6mnzflg22brhakzq@dvcduolqwhl6>
Date: Tue, 18 Mar 2025 16:24:28 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Luigi Leonardi <leonardi@...hat.com>
Cc: Michal Luczaj <mhal@...x.co>, virtualization@...ts.linux.dev,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org, Hyunwoo Kim <v4bel@...ori.io>
Subject: Re: [PATCH net-next v2] vsock/test: Add test for null ptr deref when
transport changes
On Fri, Mar 14, 2025 at 10:27:33AM +0100, Luigi Leonardi wrote:
>Add a new test to ensure that when the transport changes a null pointer
>dereference does not occur[1].
I'd add something like this:
"... does not occur. The bug was reported upstream [1] and fixed with
commit 2cb7c756f605 ("vsock/virtio: discard packets if the transport
changes")."
>
>Note that this test does not fail, but it may hang on the client side if
>it triggers a kernel oops.
In my case the test failed (I guess the other side that was still
working), so I'd say: "Note that this test may not fail in a kernel
without the fix, ..."
>
>This works by creating a socket, trying to connect to a server, and then
>executing a second connect operation on the same socket but to a
>different CID (0). This triggers a transport change. If the connect
>operation is interrupted by a signal, this could cause a null-ptr-deref.
>
>Since this bug is non-deterministic, we need to try several times. It
>is safe to assume that the bug will show up within the timeout period.
s/safe/reasonable
>
>If there is a G2H transport loaded in the system, the bug is not
>triggered and this test will always pass.
The rest LGTM.
Thanks,
Stefano
>
>[1]https://lore.kernel.org/netdev/Z2LvdTTQR7dBmPb5@v4bel-B760M-AORUS-ELITE-AX/
>
>Suggested-by: Hyunwoo Kim <v4bel@...ori.io>
>Suggested-by: Michal Luczaj <mhal@...x.co>
>Signed-off-by: Luigi Leonardi <leonardi@...hat.com>
>---
>This series introduces a new test that checks for a null pointer
>dereference that may happen when there is a transport change[1]. This
>bug was fixed in [2].
>
>Note that this test *cannot* fail, it hangs if it triggers a kernel
>oops. The intended use-case is to run it and then check if there is any
>oops in the dmesg.
>
>This test is based on Hyunwoo Kim's[3] and Michal's python
>reproducers[4].
>
>[1]https://lore.kernel.org/netdev/Z2LvdTTQR7dBmPb5@v4bel-B760M-AORUS-ELITE-AX/
>[2]https://lore.kernel.org/netdev/20250110083511.30419-1-sgarzare@redhat.com/
>[3]https://lore.kernel.org/netdev/Z2LvdTTQR7dBmPb5@v4bel-B760M-AORUS-ELITE-AX/#t
>[4]https://lore.kernel.org/netdev/2b3062e3-bdaa-4c94-a3c0-2930595b9670@rbox.co/
>---
>Changes in v2:
>- Addressed Stefano's comments:
> - Timeout is now using current_nsec()
> - Check for return values
> - Style issues
>- Added Hyunwoo Kim to Suggested-by
>- Link to v1: https://lore.kernel.org/r/20250306-test_vsock-v1-0-0320b5accf92@redhat.com
>---
> tools/testing/vsock/Makefile | 1 +
> tools/testing/vsock/vsock_test.c | 101 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 102 insertions(+)
>
>diff --git a/tools/testing/vsock/Makefile b/tools/testing/vsock/Makefile
>index 6e0b4e95e230500f99bb9c74350701a037ecd198..88211fd132d23ecdfd56ab0815580a237889e7f2 100644
>--- a/tools/testing/vsock/Makefile
>+++ b/tools/testing/vsock/Makefile
>@@ -5,6 +5,7 @@ vsock_test: vsock_test.o vsock_test_zerocopy.o timeout.o control.o util.o msg_ze
> vsock_diag_test: vsock_diag_test.o timeout.o control.o util.o
> vsock_perf: vsock_perf.o msg_zerocopy_common.o
>
>+vsock_test: LDLIBS = -lpthread
> vsock_uring_test: LDLIBS = -luring
> vsock_uring_test: control.o util.o vsock_uring_test.o timeout.o msg_zerocopy_common.o
>
>diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
>index d0f6d253ac72d08a957cb81a3c38fcc72bec5a53..d2820a67403c95bc4a7e7a16113ae2f6137b4c73 100644
>--- a/tools/testing/vsock/vsock_test.c
>+++ b/tools/testing/vsock/vsock_test.c
>@@ -23,6 +23,7 @@
> #include <sys/ioctl.h>
> #include <linux/sockios.h>
> #include <linux/time64.h>
>+#include <pthread.h>
>
> #include "vsock_test_zerocopy.h"
> #include "timeout.h"
>@@ -1788,6 +1789,101 @@ static void test_stream_connect_retry_server(const struct test_opts *opts)
> close(fd);
> }
>
>+static void *test_stream_transport_change_thread(void *vargp)
>+{
>+ pid_t *pid = (pid_t *)vargp;
>+
>+ /* We want this thread to terminate as soon as possible */
>+ if (pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL)) {
>+ perror("pthread_setcanceltype");
>+ exit(EXIT_FAILURE);
>+ }
>+
>+ while (true) {
>+ if (kill(*pid, SIGUSR1) < 0) {
>+ perror("kill");
>+ exit(EXIT_FAILURE);
>+ }
>+ }
>+ return NULL;
>+}
>+
>+static void test_transport_change_signal_handler(int signal)
>+{
>+ /* We need a custom handler for SIGUSR1 as the default one terminates the process. */
>+}
>+
>+static void test_stream_transport_change_client(const struct test_opts *opts)
>+{
>+ __sighandler_t old_handler;
>+ pid_t pid = getpid();
>+ pthread_t thread_id;
>+ time_t tout;
>+
>+ old_handler = signal(SIGUSR1, test_transport_change_signal_handler);
>+ if (old_handler == SIG_ERR) {
>+ perror("signal");
>+ exit(EXIT_FAILURE);
>+ }
>+
>+ if (pthread_create(&thread_id, NULL, test_stream_transport_change_thread, &pid)) {
>+ perror("pthread_create");
>+ exit(EXIT_FAILURE);
>+ }
>+
>+ tout = current_nsec() + TIMEOUT * NSEC_PER_SEC;
>+ do {
>+ struct sockaddr_vm sa = {
>+ .svm_family = AF_VSOCK,
>+ .svm_cid = opts->peer_cid,
>+ .svm_port = opts->peer_port,
>+ };
>+ int s;
>+
>+ s = socket(AF_VSOCK, SOCK_STREAM, 0);
>+ if (s < 0) {
>+ perror("socket");
>+ exit(EXIT_FAILURE);
>+ }
>+
>+ connect(s, (struct sockaddr *)&sa, sizeof(sa));
>+
>+ /* Set CID to 0 cause a transport change. */
>+ sa.svm_cid = 0;
>+ connect(s, (struct sockaddr *)&sa, sizeof(sa));
>+
>+ close(s);
>+ } while (current_nsec() < tout);
>+
>+ if (pthread_cancel(thread_id)) {
>+ perror("pthread_cancel");
>+ exit(EXIT_FAILURE);
>+ }
>+
>+ /* Wait for the thread to terminate */
>+ if (pthread_join(thread_id, NULL)) {
>+ perror("pthread_join");
>+ exit(EXIT_FAILURE);
>+ }
>+
>+ /* Restore the old handler */
>+ if (signal(SIGUSR1, old_handler) == SIG_ERR) {
>+ perror("signal");
>+ exit(EXIT_FAILURE);
>+ }
>+}
>+
>+static void test_stream_transport_change_server(const struct test_opts *opts)
>+{
>+ time_t tout = current_nsec() + TIMEOUT * NSEC_PER_SEC;
>+
>+ do {
>+ int s = vsock_stream_listen(VMADDR_CID_ANY, opts->peer_port);
>+
>+ close(s);
>+ } while (current_nsec() < tout);
>+}
>+
> static void test_stream_linger_client(const struct test_opts *opts)
> {
> struct linger optval = {
>@@ -1984,6 +2080,11 @@ static struct test_case test_cases[] = {
> .run_client = test_stream_linger_client,
> .run_server = test_stream_linger_server,
> },
>+ {
>+ .name = "SOCK_STREAM transport change null-ptr-deref",
>+ .run_client = test_stream_transport_change_client,
>+ .run_server = test_stream_transport_change_server,
>+ },
> {},
> };
>
>
>---
>base-commit: 4d872d51bc9d7b899c1f61534e3dbde72613f627
>change-id: 20250306-test_vsock-3e77a9c7a245
>
>Best regards,
>--
>Luigi Leonardi <leonardi@...hat.com>
>
Powered by blists - more mailing lists