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| author | Florian Weimer <fweimer@redhat.com> | 2021-05-27 15:37:35 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2021-05-27 15:37:35 +0200 |
| commit | 76b0c59e333da6fd4103e478b63522636d9d232b (patch) | |
| tree | f20e7ff7398161347494a64e7382546908e09a8c | |
| parent | 4f26956d5ba394eb3ade6c1c20b5c16864a00766 (diff) | |
| download | glibc-76b0c59e333da6fd4103e478b63522636d9d232b.zip glibc-76b0c59e333da6fd4103e478b63522636d9d232b.tar.gz glibc-76b0c59e333da6fd4103e478b63522636d9d232b.tar.bz2 | |
nptl: Install SIGSETXID handler with SA_ONSTACK [BZ #27914]
The signal is sent to all threads, some of which may have switched
to very small stacks. If they have also installed an alternate
signal stack, SA_ONSTACK makes this work. The Go runtime needs this:
runtime: C.setuid/C.setgid smashes Go stack
<https://github.com/golang/go/issues/9400>
Doing this for SIGCANCEL is less obviously beneficial and needs further
testing.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
| -rw-r--r-- | nptl/pthread_create.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c index 5680687..b7073a8 100644 --- a/nptl/pthread_create.c +++ b/nptl/pthread_create.c @@ -83,9 +83,12 @@ late_init (void) (void) __libc_sigaction (SIGCANCEL, &sa, NULL); } - /* Install the handle to change the threads' uid/gid. */ + /* Install the handle to change the threads' uid/gid. Use + SA_ONSTACK because the signal may be sent to threads that are + running with custom stacks. (This is less likely for + SIGCANCEL.) */ sa.sa_sigaction = __nptl_setxid_sighandler; - sa.sa_flags = SA_SIGINFO | SA_RESTART; + sa.sa_flags = SA_ONSTACK | SA_SIGINFO | SA_RESTART; (void) __libc_sigaction (SIGSETXID, &sa, NULL); /* The parent process might have left the signals blocked. Just in |