From: Rich Felker dalias@libc.org
[ Upstream commit 4d671d922d51907bc41f1f7f2dc737c928ae78fd ]
Asynchronous termination of a thread outside of the userspace thread library's knowledge is an unsafe operation that leaves the process in an inconsistent, corrupt, and possibly unrecoverable state. In order to make new actions that may be added in the future safe on kernels not aware of them, change the default action from SECCOMP_RET_KILL_THREAD to SECCOMP_RET_KILL_PROCESS.
Signed-off-by: Rich Felker dalias@libc.org Link: https://lore.kernel.org/r/20200829015609.GA32566@brightrain.aerifal.cx [kees: Fixed up coredump selection logic to match] Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/seccomp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 56e69203b6588..4b56c83eb3da9 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -745,7 +745,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, default: seccomp_log(this_syscall, SIGSYS, action, true); /* Dump core only if this is the last remaining thread. */ - if (action == SECCOMP_RET_KILL_PROCESS || + if (action != SECCOMP_RET_KILL_THREAD || get_nr_threads(current) == 1) { siginfo_t info;
@@ -755,10 +755,10 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, seccomp_init_siginfo(&info, this_syscall, data); do_coredump(&info); } - if (action == SECCOMP_RET_KILL_PROCESS) - do_group_exit(SIGSYS); - else + if (action == SECCOMP_RET_KILL_THREAD) do_exit(SIGSYS); + else + do_group_exit(SIGSYS); }
unreachable();