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author | Rich Felker <dalias@aerifal.cx> | 2020-07-06 18:46:57 -0400 |
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committer | Rich Felker <dalias@aerifal.cx> | 2020-07-06 18:46:57 -0400 |
commit | 52ee0dd6d5ccefcbf9b55748896c85801bfafd17 (patch) | |
tree | 81c28d3754b408c4c067316591aeba85c8fa3d8a /src/thread/pthread_kill.c | |
parent | 7cc9496a18c3fa665c286b8be41d790c795e0171 (diff) | |
download | musl-52ee0dd6d5ccefcbf9b55748896c85801bfafd17.tar.gz musl-52ee0dd6d5ccefcbf9b55748896c85801bfafd17.tar.bz2 musl-52ee0dd6d5ccefcbf9b55748896c85801bfafd17.tar.xz musl-52ee0dd6d5ccefcbf9b55748896c85801bfafd17.zip |
fix async-cancel-safety of pthread_cancel
the previous commit addressing async-signal-safety issues around
pthread_kill did not fully fix pthread_cancel, which is also required
(albeit rather irrationally) to be async-cancel-safe.
without blocking implementation-internal signals, it's possible that,
when async cancellation is enabled, a cancel signal sent by another
thread interrupts pthread_kill while the killlock for a targeted
thread is held. as a result, the calling thread will terminate due to
cancellation without ever unlocking the targeted thread's killlock,
and thus the targeted thread will be unable to exit.
Diffstat (limited to 'src/thread/pthread_kill.c')
-rw-r--r-- | src/thread/pthread_kill.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/src/thread/pthread_kill.c b/src/thread/pthread_kill.c index 446254b6..79ddb209 100644 --- a/src/thread/pthread_kill.c +++ b/src/thread/pthread_kill.c @@ -5,7 +5,10 @@ int pthread_kill(pthread_t t, int sig) { int r; sigset_t set; - __block_app_sigs(&set); + /* Block not just app signals, but internal ones too, since + * pthread_kill is used to implement pthread_cancel, which + * must be async-cancel-safe. */ + __block_all_sigs(&set); LOCK(t->killlock); r = t->tid ? -__syscall(SYS_tkill, t->tid, sig) : (sig+0U >= _NSIG ? EINVAL : 0); |