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b=OPLFbMp5APpFtxsxTti4fNjZl+zGL2kKVPIF4twuXm8Vv5JzNj5Uk/61J1WYuyd+b VFYkPbMFJlf7ujPd7iI071pGkNVX7bZEy59Ivs8GxWcWoOlaPEoxJu/82IdiMZEYMz 4LwQiANgIin1sxxhYMkYsdSSXn2aPB6uFzzLcLa0PtWvpLoGSB/8uN6t8Q9720TVUC 6ForjC4p0vkAEquj9i2NaYfeqGD8wSdrsHzFL7ZAdjoRmdQ3xID2q3ZGosVx8ld7kU KoOskmGT8Q+wDg+Kdp8I54ZiaoLJaO2T1jEuZKrClfx/pFJteTsHk2TgpgFlvfAPze gIQzq7HkgSGiw== From: Christian Brauner Date: Mon, 21 Sep 2026 15:45:00 +0200 Subject: [PATCH v3 11/17] selftests/coredump: expect PTRACE_SETSIGMASK to be refused on a user worker MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260921-work-coredump-fixes-v3-11-8e4adb1619e6@kernel.org> References: <20260921-work-coredump-fixes-v3-0-8e4adb1619e6@kernel.org> In-Reply-To: <20260921-work-coredump-fixes-v3-0-8e4adb1619e6@kernel.org> To: Oleg Nesterov , Chris Mason , linux-fsdevel@vger.kernel.org Cc: Jens Axboe , Alexander Viro , Jan Kara , NeilBrown , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, io-uring@vger.kernel.org, "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-db0b7 X-Developer-Signature: v=1; a=openpgp-sha256; l=3510; i=brauner@kernel.org; h=from:subject:message-id; bh=y1jOkzZuO9VHLKMd/1GcHI3KZB/M7wgZM5eLLCIt5GE=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWRtNLmzN7HmW9fVol0em69sXzTtfdueq2u8xY4ErL76Y PkH7qXzVnaUsjCIcTHIiimyOLSbhMst56nYbJSpATOHlQlkCAMXpwBMJOYvwy+m5xZfq4M2P9IR vVVvNX++2z6uvxmnZz0S0hUVWhr53G06wx8e3qv7RBeVTH9swcyg8tkvdNVfP1nhoDeh0q9LX2b LnuIHAA== X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: ECFC88000B X-Stat-Signature: 969y4see7sk1bwwxyow4an1mui3nqozp X-HE-Tag: 1789998346-892680 X-HE-Meta: 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 zwk3g666 LapwGcaIGlySMuD1VGwZoN8DlioisiIs3hfd2hsyycv/hehT/O61qVT4kodCQRqFF4NECU2aLiZ4aaSC2Gf6pizSBoFJgBkJ+UXBlBjSiKIEn5TS3c4uMcecDQATF27cuhYtqCneKWwOJVcTNlfrzs65brPEq/9i/UZBYDqjBEF1txuPMXtzAYO+yRlbVISS73wTHBMN89k7CyMMwHUGxKT7aMsaqAQsvPkbXwu/C7Rf+V1PWDBu3+Vo0EeNkqcJx8PUj6Rz6IYPUe3kjAYKfEbh9aqUpoEtUBBpM Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: PTRACE_SETSIGMASK returns -EPERM for a user worker now. - inject_coredump_signal() reports whether the mask could be changed - a refused mask means the injected SIGSEGV stays pending on the worker - the worker cases check that the group is alive and kill it The main thread case still dumps. Signed-off-by: Christian Brauner (Amutable) --- .../selftests/coredump/coredump_worker_test.c | 44 ++++++++++++++++------ 1 file changed, 32 insertions(+), 12 deletions(-) diff --git a/tools/testing/selftests/coredump/coredump_worker_test.c b/tools/testing/selftests/coredump/coredump_worker_test.c index 81cadde0e752..9a4270b65a6e 100644 --- a/tools/testing/selftests/coredump/coredump_worker_test.c +++ b/tools/testing/selftests/coredump/coredump_worker_test.c @@ -16,6 +16,7 @@ * SIGKILL still works. A failure leaves the stuck process behind. */ #include +#include #include #include #include @@ -255,24 +256,31 @@ static pid_t find_thread(pid_t pid, const char *prefix) /* * Attach, stop the thread with SIGSTOP, drop the signal mask that - * copy_process() gave it and resume it with SIGSEGV instead. + * copy_process() gave it and resume it with SIGSEGV. Returns 1 when the + * mask was changed, 0 when PTRACE_SETSIGMASK was refused (a user worker + * keeps its mask and the SIGSEGV stays pending), -1 on any other failure. */ -static bool inject_coredump_signal(pid_t pid, pid_t tid) +static int inject_coredump_signal(pid_t pid, pid_t tid) { __u64 mask = 0; - int status; + int status, ret = 1; if (ptrace(PTRACE_SEIZE, tid, NULL, NULL)) - return false; + return -1; if (syscall(SYS_tgkill, pid, tid, SIGSTOP)) - return false; + return -1; if (waitpid(tid, &status, __WALL) != tid) - return false; + return -1; if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) - return false; - if (ptrace(PTRACE_SETSIGMASK, tid, sizeof(mask), &mask)) - return false; - return !ptrace(PTRACE_DETACH, tid, NULL, (void *)(long)SIGSEGV); + return -1; + if (ptrace(PTRACE_SETSIGMASK, tid, sizeof(mask), &mask)) { + if (errno != EPERM) + return -1; + ret = 0; + } + if (ptrace(PTRACE_DETACH, tid, NULL, (void *)(long)SIGSEGV)) + return -1; + return ret; } /* Reap @pid within @timeout_ms, -1 when it is still there. */ @@ -333,7 +341,7 @@ static void run_dumper(struct __test_metadata *const _metadata, bool sqpoll, { bool killed = false; char path[64], c; - int ipc[2], status, fd; + int ipc[2], status, fd, ret; pid_t pid, tid; ASSERT_TRUE(set_core_pattern("/tmp/coredump.file.%p")); @@ -361,7 +369,19 @@ static void run_dumper(struct __test_metadata *const _metadata, bool sqpoll, break; } ASSERT_GT(tid, 0); - ASSERT_TRUE(inject_coredump_signal(pid, tid)); + ret = inject_coredump_signal(pid, tid); + ASSERT_GE(ret, 0); + if (!ret) { + /* The signal sits on the worker, the group must be untouched. */ + ASSERT_NE(dumper, DUMPER_MAIN); + TH_LOG("PTRACE_SETSIGMASK refused for tid %d, the SIGSEGV stays pending", tid); + ASSERT_EQ(wait_exit(pid, &status, 1000), -1); + kill(pid, SIGKILL); + ASSERT_EQ(wait_exit(pid, &status, EXIT_TIMEOUT_MS), 0); + ASSERT_TRUE(WIFSIGNALED(status)); + ASSERT_EQ(WTERMSIG(status), SIGKILL); + return; + } if (wait_exit(pid, &status, EXIT_TIMEOUT_MS)) { /* No dump. Whatever happened, SIGKILL must still work. */ -- 2.53.0