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| author | Martin Kuchta <martin.kuchta@netapp.com> | 2018-08-27 18:54:46 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2018-08-27 19:21:10 +0200 |
| commit | 1324858a3fd3d0291f9dec45f771881ba7209150 (patch) | |
| tree | e9d39899f7c16d96614985d6bb4c1a390fe1ef5f | |
| parent | 71616d59ec97fe798b69f749e7fb424bd6d2432b (diff) | |
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pthread_cond_broadcast: Fix waiters-after-spinning case [BZ #23538]
(cherry picked from commit 99ea93ca31795469d2a1f1570f17a5c39c2eb7e2)
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | NEWS | 1 | ||||
| -rw-r--r-- | nptl/pthread_cond_common.c | 8 |
3 files changed, 15 insertions, 2 deletions
@@ -1,3 +1,11 @@ +2018-08-27 Martin Kuchta <martin.kuchta@netapp.com> + Torvald Riegel <triegel@redhat.com> + + [BZ #23538] + * nptl/pthread_cond_common.c (__condvar_quiesce_and_switch_g1): + Update r to include the set wake-request flag if waiters are + remaining after spinning. + 2018-01-19 Tulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com> [BZ #22685] @@ -84,6 +84,7 @@ The following bugs are resolved with this release: [22685] powerpc: Fix syscalls during early process initialization [22715] x86-64: Properly align La_x86_64_retval to VEC_SIZE [22774] malloc: Integer overflow in malloc (CVE-2018-6551) + [23538] pthread_cond_broadcast: Fix waiters-after-spinning case Version 2.25 diff --git a/nptl/pthread_cond_common.c b/nptl/pthread_cond_common.c index 7c63ef9b89..886f0abcb3 100644 --- a/nptl/pthread_cond_common.c +++ b/nptl/pthread_cond_common.c @@ -406,8 +406,12 @@ __condvar_quiesce_and_switch_g1 (pthread_cond_t *cond, uint64_t wseq, { /* There is still a waiter after spinning. Set the wake-request flag and block. Relaxed MO is fine because this is just about - this futex word. */ - r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1); + this futex word. + + Update r to include the set wake-request flag so that the upcoming + futex_wait only blocks if the flag is still set (otherwise, we'd + violate the basic client-side futex protocol). */ + r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1) | 1; if ((r >> 1) > 0) futex_wait_simple (cond->__data.__g_refs + g1, r, private); |