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* [Bug nptl/17208] New: pthread_cond_wait may put mutex into incorrect state if mutex has elision disabled
@ 2014-07-28 6:41 robert at ocallahan dot org
2014-07-28 7:18 ` [Bug nptl/17208] " robert at ocallahan dot org
0 siblings, 1 reply; 2+ messages in thread
From: robert at ocallahan dot org @ 2014-07-28 6:41 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=17208
Bug ID: 17208
Summary: pthread_cond_wait may put mutex into incorrect state
if mutex has elision disabled
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: nptl
Assignee: unassigned at sourceware dot org
Reporter: robert at ocallahan dot org
CC: drepper.fsp at gmail dot com
pthread_cond_wait calls __pthread_mutex_cond_lock_adjust after acquiring the
mutex's futex. __pthread_mutex_cond_lock_adjust has the following code:
if (mutex->__data.__kind == PTHREAD_MUTEX_PI_RECURSIVE_NP)
++mutex->__data.__count;
I think this code should check PTHREAD_MUTEX_TYPE(mutex->__data.__kind).
Otherwise, if the mutex is recursive but __kind has the
PTHREAD_MUTEX_ELISION_NP or PTHREAD_MUTEX_NO_ELISION_NP, __count will not be
incremented and a later pthread_mutex_unlock of the mutex goes wrong,
decrementing __count from 0 to 0xffffffff and failing to unlock the mutex.
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2014-07-28 6:41 [Bug nptl/17208] New: pthread_cond_wait may put mutex into incorrect state if mutex has elision disabled robert at ocallahan dot org
2014-07-28 7:18 ` [Bug nptl/17208] " robert at ocallahan dot org
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