From 1227f793a3903adede083aba7cf3dcf0e4fba02d Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Tue, 24 Dec 2024 01:21:02 -0500
Subject: sighook: Preserve the exact siginfo_t in reraise() on Linux
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=66dd34ad31e5963d72a700ec3f2449291d322921
---
src/sighook.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/src/sighook.c b/src/sighook.c
index e74bb78..6269614 100644
--- a/src/sighook.c
+++ b/src/sighook.c
@@ -32,6 +32,10 @@
#include <stdlib.h>
#include <unistd.h>
+#if __linux__
+# include <sys/syscall.h>
+#endif
+
// NetBSD opens a file descriptor for each sem_init()
#if defined(_POSIX_SEMAPHORES) && !__NetBSD__
# define BFS_POSIX_SEMAPHORES _POSIX_SEMAPHORES
@@ -385,7 +389,9 @@ static bool is_fatal(int sig) {
/** Reraise a fatal signal. */
_noreturn
-static void reraise(int sig) {
+static void reraise(siginfo_t *info) {
+ int sig = info->si_signo;
+
// Restore the default signal action
if (signal(sig, SIG_DFL) == SIG_ERR) {
goto fail;
@@ -399,6 +405,13 @@ static void reraise(int sig) {
goto fail;
}
+#if __linux__
+ // On Linux, try to re-raise the exact siginfo_t (since 3.9, a process can
+ // signal itself with any siginfo_t)
+ pid_t tid = syscall(SYS_gettid);
+ syscall(SYS_rt_tgsigqueueinfo, getpid(), tid, sig, info);
+#endif
+
raise(sig);
fail:
abort();
@@ -462,7 +475,7 @@ static void sigdispatch(int sig, siginfo_t *info, void *context) {
return;
}
#endif
- reraise(sig);
+ reraise(info);
}
// https://pubs.opengroup.org/onlinepubs/9799919799/functions/V2_chap02.html#tag_16_04_04
@@ -482,7 +495,7 @@ static void sigdispatch(int sig, siginfo_t *info, void *context) {
if (!(flags & SH_CONTINUE) && is_fatal(sig)) {
list = siglist(0);
run_hooks(list, sig, info);
- reraise(sig);
+ reraise(info);
}
errno = error;
--
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