diff options
| -rw-r--r-- | ChangeLog | 12 | ||||
| -rw-r--r-- | nptl/pthread_mutex_unlock.c | 12 | ||||
| -rw-r--r-- | sysdeps/nptl/lowlevellock.h | 18 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/lowlevellock-futex.h | 9 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/sparc/lowlevellock.h | 6 |
5 files changed, 44 insertions, 13 deletions
diff --git a/ChangeLog b/ChangeLog index 9063848e27..4ba6ee4a13 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,15 @@ +2015-12-23 Torvald Riegel <triegel@redhat.com> + + [BZ #13690] + * sysdeps/nptl/lowlevellock.h (__lll_unlock): Do not access the lock + after releasing it. + (__lll_robust_unlock): Likewise. + * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise. + * sysdeps/unix/sysv/linux/sparc/lowlevellock.h (lll_unlock): Likewise. + (lll_robust_unlock): Likewise. + * sysdeps/unix/sysv/linux/lowlevellock-futex.h (__lll_private_flag): + Prevent warnings in callers. + 2015-12-23 Florian Weimer <fweimer@redhat.com> * malloc/arena.c (list_lock): Update comment. diff --git a/nptl/pthread_mutex_unlock.c b/nptl/pthread_mutex_unlock.c index c078f7ebe3..e2cd52411f 100644 --- a/nptl/pthread_mutex_unlock.c +++ b/nptl/pthread_mutex_unlock.c @@ -230,16 +230,18 @@ __pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr) /* One less user. */ --mutex->__data.__nusers; - /* Unlock. */ + /* Unlock. Load all necessary mutex data before releasing the mutex + to not violate the mutex destruction requirements (see + lll_unlock). */ + int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP; + int private = (robust + ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex) + : PTHREAD_MUTEX_PSHARED (mutex)); if ((mutex->__data.__lock & FUTEX_WAITERS) != 0 || atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock, 0, THREAD_GETMEM (THREAD_SELF, tid))) { - int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP; - int private = (robust - ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex) - : PTHREAD_MUTEX_PSHARED (mutex)); INTERNAL_SYSCALL_DECL (__err); INTERNAL_SYSCALL (futex, __err, 2, &mutex->__data.__lock, __lll_private_flag (FUTEX_UNLOCK_PI, private)); diff --git a/sysdeps/nptl/lowlevellock.h b/sysdeps/nptl/lowlevellock.h index 27f41424ea..7d41ef0335 100644 --- a/sysdeps/nptl/lowlevellock.h +++ b/sysdeps/nptl/lowlevellock.h @@ -191,14 +191,21 @@ extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *, that's cast to void. */ /* Unconditionally set FUTEX to 0 (not acquired), releasing the lock. If FUTEX was >1 (acquired, possibly with waiters), then wake any waiters. The waiter - that acquires the lock will set FUTEX to >1. */ + that acquires the lock will set FUTEX to >1. + Evaluate PRIVATE before releasing the lock so that we do not violate the + mutex destruction requirements. Specifically, we need to ensure that + another thread can destroy the mutex (and reuse its memory) once it + acquires the lock and when there will be no further lock acquisitions; + thus, we must not access the lock after releasing it, or those accesses + could be concurrent with mutex destruction or reuse of the memory. */ #define __lll_unlock(futex, private) \ ((void) \ ({ \ int *__futex = (futex); \ + int __private = (private); \ int __oldval = atomic_exchange_rel (__futex, 0); \ if (__glibc_unlikely (__oldval > 1)) \ - lll_futex_wake (__futex, 1, private); \ + lll_futex_wake (__futex, 1, __private); \ })) #define lll_unlock(futex, private) \ __lll_unlock (&(futex), private) @@ -209,14 +216,17 @@ extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *, that's cast to void. */ /* Unconditionally set FUTEX to 0 (not acquired), releasing the lock. If FUTEX had FUTEX_WAITERS set then wake any waiters. The waiter that acquires the - lock will set FUTEX_WAITERS. */ + lock will set FUTEX_WAITERS. + Evaluate PRIVATE before releasing the lock so that we do not violate the + mutex destruction requirements (see __lll_unlock). */ #define __lll_robust_unlock(futex, private) \ ((void) \ ({ \ int *__futex = (futex); \ + int __private = (private); \ int __oldval = atomic_exchange_rel (__futex, 0); \ if (__glibc_unlikely (__oldval & FUTEX_WAITERS)) \ - lll_futex_wake (__futex, 1, private); \ + lll_futex_wake (__futex, 1, __private); \ })) #define lll_robust_unlock(futex, private) \ __lll_robust_unlock (&(futex), private) diff --git a/sysdeps/unix/sysv/linux/lowlevellock-futex.h b/sysdeps/unix/sysv/linux/lowlevellock-futex.h index 59f6627bdb..40825f0306 100644 --- a/sysdeps/unix/sysv/linux/lowlevellock-futex.h +++ b/sysdeps/unix/sysv/linux/lowlevellock-futex.h @@ -54,8 +54,13 @@ #if IS_IN (libc) || IS_IN (rtld) /* In libc.so or ld.so all futexes are private. */ # ifdef __ASSUME_PRIVATE_FUTEX -# define __lll_private_flag(fl, private) \ - ((fl) | FUTEX_PRIVATE_FLAG) +# define __lll_private_flag(fl, private) \ + ({ \ + /* Prevent warnings in callers of this macro. */ \ + int __lll_private_flag_priv __attribute__ ((unused)); \ + __lll_private_flag_priv = (private); \ + ((fl) | FUTEX_PRIVATE_FLAG); \ + }) # else # define __lll_private_flag(fl, private) \ ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex)) diff --git a/sysdeps/unix/sysv/linux/sparc/lowlevellock.h b/sysdeps/unix/sysv/linux/sparc/lowlevellock.h index 7608c01d17..9fa73371fc 100644 --- a/sysdeps/unix/sysv/linux/sparc/lowlevellock.h +++ b/sysdeps/unix/sysv/linux/sparc/lowlevellock.h @@ -126,17 +126,19 @@ __lll_robust_timedlock (int *futex, const struct timespec *abstime, #define lll_unlock(lock, private) \ ((void) ({ \ int *__futex = &(lock); \ + int __private = (private); \ int __val = atomic_exchange_24_rel (__futex, 0); \ if (__glibc_unlikely (__val > 1)) \ - lll_futex_wake (__futex, 1, private); \ + lll_futex_wake (__futex, 1, __private); \ })) #define lll_robust_unlock(lock, private) \ ((void) ({ \ int *__futex = &(lock); \ + int __private = (private); \ int __val = atomic_exchange_rel (__futex, 0); \ if (__glibc_unlikely (__val & FUTEX_WAITERS)) \ - lll_futex_wake (__futex, 1, private); \ + lll_futex_wake (__futex, 1, __private); \ })) #define lll_islocked(futex) \ |