send_signal_locked() should not change the caller's siginfo. Make that part of the type and keep the local rewrite on its copy.
Suggested-by: Oleg Nesterov <[email protected]> Signed-off-by: Bradley Morgan <[email protected]> --- Changes since v1: - New patch from Oleg's suggestion. - Link to Oleg's suggestion: https://lore.kernel.org/all/[email protected]/T/#m5f8a2d54928efff41de539969b68149e1ec5fca4 include/linux/signal.h | 2 +- include/trace/events/signal.h | 4 ++-- kernel/signal.c | 20 +++++++++++--------- 3 files changed, 14 insertions(+), 12 deletions(-) diff --git a/include/linux/signal.h b/include/linux/signal.h index f19816832f05..a1ba8c5973c6 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -283,7 +283,7 @@ extern int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p, enum pid_type type); extern int group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p, enum pid_type type); -extern int send_signal_locked(int sig, struct kernel_siginfo *info, +extern int send_signal_locked(int sig, const struct kernel_siginfo *info, struct task_struct *p, enum pid_type type); extern int sigprocmask(int, sigset_t *, sigset_t *); extern void set_current_blocked(sigset_t *); diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h index 1db7e4b07c01..05a46135ee34 100644 --- a/include/trace/events/signal.h +++ b/include/trace/events/signal.h @@ -49,8 +49,8 @@ enum { */ TRACE_EVENT(signal_generate, - TP_PROTO(int sig, struct kernel_siginfo *info, struct task_struct *task, - int group, int result), + TP_PROTO(int sig, const struct kernel_siginfo *info, + struct task_struct *task, int group, int result), TP_ARGS(sig, info, task, group, result), diff --git a/kernel/signal.c b/kernel/signal.c index d72d9be3a992..26e8b8e1d03c 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1037,7 +1037,7 @@ static inline bool legacy_queue(struct sigpending *signals, int sig) return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } -static int __send_signal_locked(int sig, struct kernel_siginfo *info, +static int __send_signal_locked(int sig, const struct kernel_siginfo *info, struct task_struct *t, enum pid_type type, bool force) { struct sigpending *pending; @@ -1154,7 +1154,7 @@ static int __send_signal_locked(int sig, struct kernel_siginfo *info, return ret; } -static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) +static inline bool has_si_pid_and_uid(const struct kernel_siginfo *info) { bool ret = false; switch (siginfo_layout(info->si_signo, info->si_code)) { @@ -1178,10 +1178,11 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info) return ret; } -int send_signal_locked(int sig, struct kernel_siginfo *info, +int send_signal_locked(int sig, const struct kernel_siginfo *info, struct task_struct *t, enum pid_type type) { struct kernel_siginfo rewritten; + const struct kernel_siginfo *send_info = info; /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */ bool force = false; @@ -1196,26 +1197,27 @@ int send_signal_locked(int sig, struct kernel_siginfo *info, struct user_namespace *t_user_ns; rewritten = *info; - info = &rewritten; + send_info = &rewritten; rcu_read_lock(); t_user_ns = task_cred_xxx(t, user_ns); if (current_user_ns() != t_user_ns) { - kuid_t uid = make_kuid(current_user_ns(), info->si_uid); - info->si_uid = from_kuid_munged(t_user_ns, uid); + kuid_t uid = make_kuid(current_user_ns(), rewritten.si_uid); + + rewritten.si_uid = from_kuid_munged(t_user_ns, uid); } rcu_read_unlock(); /* A kernel generated signal? */ - force = (info->si_code == SI_KERNEL); + force = (rewritten.si_code == SI_KERNEL); /* From an ancestor pid namespace? */ if (!task_pid_nr_ns(current, task_active_pid_ns(t))) { - info->si_pid = 0; + rewritten.si_pid = 0; force = true; } } - return __send_signal_locked(sig, info, t, type, force); + return __send_signal_locked(sig, send_info, t, type, force); } static void print_fatal_signal(int signr) -- 2.53.0
