fix race condition in pthread_kill

if thread id was reused by the kernel between the time pthread_kill
read it from the userspace pthread_t object and the time of the tgkill
syscall, a signal could be sent to the wrong thread. the tgkill
syscall was supposed to prevent this race (versus the old tkill
syscall) but it can't; it can only help in the case where the tid is
reused in a different process, but not when the tid is reused in the
same process.

the only solution i can see is an extra lock to prevent threads from
exiting while another thread is trying to pthread_kill them. it should
be very very cheap in the non-contended case.

This commit is contained in:

Rich Felker

2011-06-14 01:35:51 -04:00

parent f58c8a0f39

commit 7779dbd266

3 changed files with 8 additions and 1 deletions

									
										src/internal/pthread_impl.h
									
		+1
		
												View File
												
				@@ -46,6 +46,7 @@ struct pthread {

					int unblock_cancel;

					int delete_timer;

					locale_t locale;

					int killlock;

				};

				struct __timer {