RepoMirrors/musl
1
0
Fork 0
mirror of git://git.musl-libc.org/musl synced 2025-01-25 08:03:04 +00:00
Code Issues Packages Projects Releases Wiki Activity

fix unintended observability of SIGABRT disposition reset via sigaction

Browse Source 
the existing abort locking logic in sigaction only accounted for
attempts to change the disposition, not attempts to observe the change
made by abort.

unfortunately the change is still observable in at least one other
place: inheritance of signal dispositions across exec and posix_spawn.
fixing these is a separate task and it's not even clear whether a
complete fix is possible.
This commit is contained in:
Rich Felker 2020-10-01 12:18:18 -04:00
parent bd153422f2
commit 25ea9f712c
1 changed files with 8 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
src/signal/sigaction.c
View File

@ -21,6 +21,13 @@ int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigact
{
struct k_sigaction ksa, ksa_old;
unsigned long set[_NSIG/(8*sizeof(long))];
/* Doing anything with the disposition of SIGABRT requires a lock,
* so that it cannot be changed while abort is terminating the
* process and so any change made by abort can't be observed. */
if (sig == SIGABRT) {
__block_all_sigs(&set);
LOCK(__abort_lock);
}
if (sa) {
if ((uintptr_t)sa->sa_handler > 1UL) {
a_or_l(handler_set+(sig-1)/(8*sizeof(long)),
@ -44,21 +51,13 @@ int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigact
a_store(&__eintr_valid_flag, 1);
}
}
/* Changing the disposition of SIGABRT to anything but
* SIG_DFL requires a lock, so that it cannot be changed
* while abort is terminating the process after simply
* calling raise(SIGABRT) failed to do so. */
if (sa->sa_handler != SIG_DFL && sig == SIGABRT) {
__block_all_sigs(&set);
LOCK(__abort_lock);
}
ksa.handler = sa->sa_handler;
ksa.flags = sa->sa_flags | SA_RESTORER;
ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
memcpy(&ksa.mask, &sa->sa_mask, _NSIG/8);
}
int r = __syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, _NSIG/8);
if (sig == SIGABRT && sa && sa->sa_handler != SIG_DFL) {
if (sig == SIGABRT) {
UNLOCK(__abort_lock);
__restore_sigs(&set);
}