GNU C Library master sources branch master updated. glibc-2.23-499-ga3b4733

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=a3b473373ee43a292f5ec68a7fda6b9cfb26a9b0

commit a3b473373ee43a292f5ec68a7fda6b9cfb26a9b0
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Jun 21 21:29:21 2016 +0200

    malloc: Avoid premature fallback to mmap [BZ #20284]
    
    Before this change, the while loop in reused_arena which avoids
    returning a corrupt arena would never execute its body if the selected
    arena were not corrupt.  As a result, result == begin after the loop,
    and the function returns NULL, triggering fallback to mmap.

diff --git a/ChangeLog b/ChangeLog
index 437fb6d..e418cc0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2016-06-21  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #20284]
+	* malloc/arena.c (reused_arena): Do not return NULL if we start
+	out with a non-corrupted arena.
+
 2016-06-21 Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* misc/Makefile (tests): Add tst-preadvwritev and tst-preadvwritev64.
diff --git a/malloc/arena.c b/malloc/arena.c
index ed5a4d5..229783f 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -771,14 +771,12 @@ reused_arena (mstate avoid_arena)
     {
       result = result->next;
       if (result == begin)
-	break;
+	/* We looped around the arena list.  We could not find any
+	   arena that was either not corrupted or not the one we
+	   wanted to avoid.  */
+	return NULL;
     }
 
-  /* We could not find any arena that was either not corrupted or not the one
-     we wanted to avoid.  */
-  if (result == begin || result == avoid_arena)
-    return NULL;
-
   /* No arena available without contention.  Wait for the next in line.  */
   LIBC_PROBE (memory_arena_reuse_wait, 3, &result->mutex, result, avoid_arena);
   (void) mutex_lock (&result->mutex);

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

Summary of changes:
 ChangeLog      |    6 ++++++
 malloc/arena.c |   10 ++++------
 2 files changed, 10 insertions(+), 6 deletions(-)


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