diff options
| -rw-r--r-- | NEWS | 1 | ||||
| -rw-r--r-- | nptl/pthread_create.c | 12 | ||||
| -rw-r--r-- | sysdeps/pthread/Makefile | 1 | ||||
| -rw-r--r-- | sysdeps/pthread/tst-pthread-setuid-loop.c | 61 |
4 files changed, 73 insertions, 2 deletions
@@ -13,6 +13,7 @@ The following bugs are resolved with this release: [19193] nptl: pthread_kill, pthread_cancel should not fail after exit [28036] Incorrect types for pthread_mutexattr_set/getrobust_np [28182] _TIME_BITS=64 in C++ has issues with fcntl, ioctl, prctl + [28361] nptl: Avoid setxid deadlock with blocked signals in thread exit Version 2.34 diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c index 33b426fc68..bc213f0bc4 100644 --- a/nptl/pthread_create.c +++ b/nptl/pthread_create.c @@ -488,8 +488,16 @@ start_thread (void *arg) /* This prevents sending a signal from this thread to itself during its final stages. This must come after the exit call above - because atexit handlers must not run with signals blocked. */ - __libc_signal_block_all (NULL); + because atexit handlers must not run with signals blocked. + + Do not block SIGSETXID. The setxid handshake below expects the + signal to be delivered. (SIGSETXID cannot run application code, + nor does it use pthread_kill.) Reuse the pd->sigmask space for + computing the signal mask, to save stack space. */ + __sigfillset (&pd->sigmask); + __sigdelset (&pd->sigmask, SIGSETXID); + INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &pd->sigmask, NULL, + __NSIG_BYTES); /* Tell __pthread_kill_internal that this thread is about to exit. If there is a __pthread_kill_internal in progress, this delays diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile index 48dba717a1..d4bd2d4e3e 100644 --- a/sysdeps/pthread/Makefile +++ b/sysdeps/pthread/Makefile @@ -118,6 +118,7 @@ tests += tst-cnd-basic tst-mtx-trylock tst-cnd-broadcast \ tst-unload \ tst-unwind-thread \ tst-pt-vfork1 tst-pt-vfork2 tst-vfork1x tst-vfork2x \ + tst-pthread-setuid-loop \ tst-pthread_cancel-exited \ tst-pthread_cancel-select-loop \ tst-pthread_kill-exited \ diff --git a/sysdeps/pthread/tst-pthread-setuid-loop.c b/sysdeps/pthread/tst-pthread-setuid-loop.c new file mode 100644 index 0000000000..fda2a49b7f --- /dev/null +++ b/sysdeps/pthread/tst-pthread-setuid-loop.c @@ -0,0 +1,61 @@ +/* Test that setuid, pthread_create, thread exit do not deadlock (bug 28361). + Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <support/check.h> +#include <support/xthread.h> +#include <unistd.h> + +/* How many threads to launch during each iteration. */ +enum { threads = 4 }; + +/* How many iterations to perform. This value seems to reproduce + bug 28361 in a bout one in three runs. */ +enum { iterations = 5000 }; + +/* Cache of the real user ID used by setuid_thread. */ +static uid_t uid; + +/* Start routine for the threads. */ +static void * +setuid_thread (void *closure) +{ + TEST_COMPARE (setuid (uid), 0); + return NULL; +} + +static int +do_test (void) +{ + /* The setxid machinery is still invoked even if the UID is + unchanged. (The kernel might reset other credentials as part of + the system call.) */ + uid = getuid (); + + for (int i = 0; i < iterations; ++i) + { + pthread_t thread_ids[threads]; + for (int j = 0; j < threads; ++j) + thread_ids[j] = xpthread_create (NULL, setuid_thread, NULL); + for (int j = 0; j < threads; ++j) + xpthread_join (thread_ids[j]); + } + + return 0; +} + +#include <support/test-driver.c> |