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Message-ID: <CAJqdLrpzR012WmcAJ2TP2cNghYzMz4aQsvEeNx1neEkD7LULug@mail.gmail.com>
Date: Tue, 4 Nov 2025 10:18:57 +0100
From: Alexander Mikhalitsyn <alexander@...alicyn.com>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
Amir Goldstein <amir73il@...il.com>, Aleksa Sarai <cyphar@...har.com>,
Yu Watanabe <watanabe.yu+github@...il.com>, Josef Bacik <josef@...icpanda.com>,
Jeff Layton <jlayton@...nel.org>, Jann Horn <jannh@...gle.com>,
Luca Boccassi <luca.boccassi@...il.com>, linux-kernel@...r.kernel.org,
Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
Lennart Poettering <lennart@...ttering.net>, Mike Yuan <me@...dnzj.com>,
Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>
Subject: Re: [PATCH 21/22] selftests/coredump: add first PIDFD_INFO_COREDUMP_SIGNAL
test
Am Di., 28. Okt. 2025 um 09:47 Uhr schrieb Christian Brauner
<brauner@...nel.org>:
>
> Verify that when using simple socket-based coredump (@ pattern),
> the coredump_signal field is correctly exposed as SIGSEGV.
>
> Signed-off-by: Christian Brauner <brauner@...nel.org>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
> ---
> .../selftests/coredump/coredump_socket_test.c | 146 +++++++++++++++++++++
> 1 file changed, 146 insertions(+)
>
> diff --git a/tools/testing/selftests/coredump/coredump_socket_test.c b/tools/testing/selftests/coredump/coredump_socket_test.c
> index da558a0e37aa..9d5507fa75ec 100644
> --- a/tools/testing/selftests/coredump/coredump_socket_test.c
> +++ b/tools/testing/selftests/coredump/coredump_socket_test.c
> @@ -430,6 +430,152 @@ TEST_F(coredump, socket_no_listener)
> wait_and_check_coredump_server(pid_coredump_server, _metadata, self);
> }
>
> +/*
> + * Test: PIDFD_INFO_COREDUMP_SIGNAL via simple socket coredump
> + *
> + * Verify that when using simple socket-based coredump (@ pattern),
> + * the coredump_signal field is correctly exposed as SIGSEGV.
> + */
> +TEST_F(coredump, socket_coredump_signal_sigsegv)
> +{
> + int pidfd, ret, status;
> + pid_t pid, pid_coredump_server;
> + struct pidfd_info info = {};
> + int ipc_sockets[2];
> + char c;
> +
> + ASSERT_TRUE(set_core_pattern("@/tmp/coredump.socket"));
> +
> + ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);
> + ASSERT_EQ(ret, 0);
> +
> + pid_coredump_server = fork();
> + ASSERT_GE(pid_coredump_server, 0);
> + if (pid_coredump_server == 0) {
> + int fd_server = -1, fd_coredump = -1, fd_peer_pidfd = -1, fd_core_file = -1;
> + int exit_code = EXIT_FAILURE;
> +
> + close(ipc_sockets[0]);
> +
> + fd_server = create_and_listen_unix_socket("/tmp/coredump.socket");
> + if (fd_server < 0) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: create_and_listen_unix_socket failed: %m\n");
> + goto out;
> + }
> +
> + if (write_nointr(ipc_sockets[1], "1", 1) < 0) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: write_nointr to ipc socket failed: %m\n");
> + goto out;
> + }
> +
> + close(ipc_sockets[1]);
> +
> + fd_coredump = accept4(fd_server, NULL, NULL, SOCK_CLOEXEC);
> + if (fd_coredump < 0) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: accept4 failed: %m\n");
> + goto out;
> + }
> +
> + fd_peer_pidfd = get_peer_pidfd(fd_coredump);
> + if (fd_peer_pidfd < 0) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: get_peer_pidfd failed\n");
> + goto out;
> + }
> +
> + if (!get_pidfd_info(fd_peer_pidfd, &info)) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: get_pidfd_info failed\n");
> + goto out;
> + }
> +
> + if (!(info.mask & PIDFD_INFO_COREDUMP)) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: PIDFD_INFO_COREDUMP not set in mask\n");
> + goto out;
> + }
> +
> + if (!(info.coredump_mask & PIDFD_COREDUMPED)) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: PIDFD_COREDUMPED not set in coredump_mask\n");
> + goto out;
> + }
> +
> + /* Verify coredump_signal is available and correct */
> + if (!(info.mask & PIDFD_INFO_COREDUMP_SIGNAL)) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: PIDFD_INFO_COREDUMP_SIGNAL not set in mask\n");
> + goto out;
> + }
> +
> + if (info.coredump_signal != SIGSEGV) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: coredump_signal=%d, expected SIGSEGV=%d\n",
> + info.coredump_signal, SIGSEGV);
> + goto out;
> + }
> +
> + fd_core_file = open_coredump_tmpfile(self->fd_tmpfs_detached);
> + if (fd_core_file < 0) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: open_coredump_tmpfile failed: %m\n");
> + goto out;
> + }
> +
> + for (;;) {
> + char buffer[4096];
> + ssize_t bytes_read, bytes_write;
> +
> + bytes_read = read(fd_coredump, buffer, sizeof(buffer));
> + if (bytes_read < 0) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: read from coredump socket failed: %m\n");
> + goto out;
> + }
> +
> + if (bytes_read == 0)
> + break;
> +
> + bytes_write = write(fd_core_file, buffer, bytes_read);
> + if (bytes_read != bytes_write) {
> + fprintf(stderr, "socket_coredump_signal_sigsegv: write to core file failed (read=%zd, write=%zd): %m\n",
> + bytes_read, bytes_write);
> + goto out;
> + }
> + }
> +
> + exit_code = EXIT_SUCCESS;
> + fprintf(stderr, "socket_coredump_signal_sigsegv: completed successfully\n");
> +out:
> + if (fd_core_file >= 0)
> + close(fd_core_file);
> + if (fd_peer_pidfd >= 0)
> + close(fd_peer_pidfd);
> + if (fd_coredump >= 0)
> + close(fd_coredump);
> + if (fd_server >= 0)
> + close(fd_server);
> + _exit(exit_code);
> + }
> + self->pid_coredump_server = pid_coredump_server;
> +
> + EXPECT_EQ(close(ipc_sockets[1]), 0);
> + ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1);
> + EXPECT_EQ(close(ipc_sockets[0]), 0);
> +
> + pid = fork();
> + ASSERT_GE(pid, 0);
> + if (pid == 0)
> + crashing_child();
> +
> + pidfd = sys_pidfd_open(pid, 0);
> + ASSERT_GE(pidfd, 0);
> +
> + waitpid(pid, &status, 0);
> + ASSERT_TRUE(WIFSIGNALED(status));
> + ASSERT_EQ(WTERMSIG(status), SIGSEGV);
> + ASSERT_TRUE(WCOREDUMP(status));
> +
> + ASSERT_TRUE(get_pidfd_info(pidfd, &info));
> + ASSERT_TRUE(!!(info.mask & PIDFD_INFO_COREDUMP));
> + ASSERT_TRUE(!!(info.mask & PIDFD_INFO_COREDUMP_SIGNAL));
> + ASSERT_EQ(info.coredump_signal, SIGSEGV);
> +
> + wait_and_check_coredump_server(pid_coredump_server, _metadata, self);
> +}
> +
> TEST_F(coredump, socket_invalid_paths)
> {
> ASSERT_FALSE(set_core_pattern("@ /tmp/coredump.socket"));
>
> --
> 2.47.3
>
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