From 4febce44cfebcb490b196d5d10ae9f403ca4c956 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 1 Oct 2024 10:42:03 +0200 Subject: posix-timers: Cure si_sys_private race The si_sys_private member of the siginfo which is embedded in the preallocated sigqueue is used by the posix timer code to decide whether a timer must be reprogrammed on signal delivery. The handling of this is racy as a long standing comment in that code documents. It is modified with the timer lock held, but without sighand lock being held. The actual signal delivery code checks for it under sighand lock without holding the timer lock. Hand the new value to send_sigqueue() as argument and store it with sighand lock held. This is an intermediate change to address this issue. The arguments to this function will be cleanup in subsequent changes. Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/all/20241001083835.434338954@linutronix.de --- include/linux/sched/signal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/sched') diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index c8ed09ac29ac..bd9f569231d9 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -340,7 +340,7 @@ extern int send_sig(int, struct task_struct *, int); extern int zap_other_threads(struct task_struct *p); extern struct sigqueue *sigqueue_alloc(void); extern void sigqueue_free(struct sigqueue *); -extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type); +extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type, int si_private); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); static inline void clear_notify_signal(void) -- cgit v1.2.3 From 0360ed14d9826678a50fa2b873e522a24cd3c018 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 5 Nov 2024 09:14:42 +0100 Subject: signal: Refactor send_sigqueue() To handle posix timers which have their signal ignored via SIG_IGN properly it is required to requeue a ignored signal for delivery when SIG_IGN is lifted so the timer gets rearmed. Split the required code out of send_sigqueue() so it can be reused in context of sigaction(). While at it rename send_sigqueue() to posixtimer_send_sigqueue() so its clear what this is about. Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/all/20241105064213.586453412@linutronix.de --- include/linux/sched/signal.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/sched') diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index bd9f569231d9..36283c1c55e9 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -340,7 +340,6 @@ extern int send_sig(int, struct task_struct *, int); extern int zap_other_threads(struct task_struct *p); extern struct sigqueue *sigqueue_alloc(void); extern void sigqueue_free(struct sigqueue *); -extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type, int si_private); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); static inline void clear_notify_signal(void) -- cgit v1.2.3 From c2a4796a154bb952be1106911841aab2c8c17c4d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 5 Nov 2024 09:14:46 +0100 Subject: signal: Cleanup unused posix-timer leftovers Remove the leftovers of sigqueue preallocation as it's not longer used. Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/all/20241105064213.786506636@linutronix.de --- include/linux/sched/signal.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/sched') diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 36283c1c55e9..02972fd41931 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -338,8 +338,6 @@ extern void force_fatal_sig(int); extern void force_exit_sig(int); extern int send_sig(int, struct task_struct *, int); extern int zap_other_threads(struct task_struct *p); -extern struct sigqueue *sigqueue_alloc(void); -extern void sigqueue_free(struct sigqueue *); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); static inline void clear_notify_signal(void) -- cgit v1.2.3 From 69f032c92cf883ea74a4b69ba3d91317aa6f174e Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 5 Nov 2024 09:14:49 +0100 Subject: signal: Provide ignored_posix_timers list To prepare for handling posix timer signals on sigaction(SIG_IGN) properly, add a list to task::signal. This list will be used to queue posix timers so their signal can be requeued when SIG_IGN is lifted later. Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/all/20241105064213.920101900@linutronix.de --- include/linux/sched/signal.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/sched') diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 02972fd41931..d5d03d919df8 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -138,6 +138,7 @@ struct signal_struct { /* POSIX.1b Interval Timers */ unsigned int next_posix_timer_id; struct hlist_head posix_timers; + struct hlist_head ignored_posix_timers; /* ITIMER_REAL timer for the process */ struct hrtimer real_timer; -- cgit v1.2.3