GNU C Library master sources branch master updated. glibc-2.23-120-g7a25d6a

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=7a25d6a84df9fea56963569ceccaaf7c2a88f161

commit 7a25d6a84df9fea56963569ceccaaf7c2a88f161
Author: Nick Alcock <nick.alcock@oracle.com>
Date:   Wed Mar 23 13:40:14 2016 +0100

    x86, pthread_cond_*wait: Do not depend on %eax not being clobbered
    
    The x86-specific versions of both pthread_cond_wait and
    pthread_cond_timedwait have (in their fall-back-to-futex-wait slow
    paths) calls to __pthread_mutex_cond_lock_adjust followed by
    __pthread_mutex_unlock_usercnt, which load the parameters before the
    first call but then assume that the first parameter, in %eax, will
    survive unaffected.  This happens to have been true before now, but %eax
    is a call-clobbered register, and this assumption is not safe: it could
    change at any time, at GCC's whim, and indeed the stack-protector canary
    checking code clobbers %eax while checking that the canary is
    uncorrupted.
    
    So reload %eax before calling __pthread_mutex_unlock_usercnt.  (Do this
    unconditionally, even when stack-protection is not in use, because it's
    the right thing to do, it's a slow path, and anything else is dicing
    with death.)
    
    	* sysdeps/unix/sysv/linux/i386/pthread_cond_timedwait.S: Reload
    	call-clobbered %eax on retry path.
    	* sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S: Likewise.

diff --git a/ChangeLog b/ChangeLog
index 54454a5..b7574b0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2016-03-23  Nick Alcock  <nick.alcock@oracle.com>
+
+	* sysdeps/unix/sysv/linux/i386/pthread_cond_timedwait.S: Reload
+        call-clobbered %eax on retry path.
+        * sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S: Likewise.
+
 2016-03-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S (MEMCPY):
diff --git a/sysdeps/unix/sysv/linux/i386/pthread_cond_timedwait.S b/sysdeps/unix/sysv/linux/i386/pthread_cond_timedwait.S
index 96f8a8d..6256376 100644
--- a/sysdeps/unix/sysv/linux/i386/pthread_cond_timedwait.S
+++ b/sysdeps/unix/sysv/linux/i386/pthread_cond_timedwait.S
@@ -297,6 +297,7 @@ __pthread_cond_timedwait:
 	   correctly.  */
 	movl	dep_mutex(%ebx), %eax
 	call	__pthread_mutex_cond_lock_adjust
+	movl	dep_mutex(%ebx), %eax
 	xorl	%edx, %edx
 	call	__pthread_mutex_unlock_usercnt
 	jmp	8b
diff --git a/sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S b/sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S
index 94302b0..5016718 100644
--- a/sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S
+++ b/sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S
@@ -309,6 +309,7 @@ __pthread_cond_wait:
 	   correctly.  */
 	movl	dep_mutex(%ebx), %eax
 	call    __pthread_mutex_cond_lock_adjust
+	movl	dep_mutex(%ebx), %eax
 	xorl	%edx, %edx
 	call	__pthread_mutex_unlock_usercnt
 	jmp	8b

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                                          |    6 ++++++
 .../unix/sysv/linux/i386/pthread_cond_timedwait.S  |    1 +
 sysdeps/unix/sysv/linux/i386/pthread_cond_wait.S   |    1 +
 3 files changed, 8 insertions(+), 0 deletions(-)


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