From 60022fbfba872422993caf6130ad4b92e74bb356 Mon Sep 17 00:00:00 2001 From: Florian Weimer <fweimer@redhat.com> Date: Tue, 21 Jun 2016 21:29:21 +0200 Subject: [PATCH] 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. (cherry picked from commit a3b473373ee43a292f5ec68a7fda6b9cfb26a9b0) --- ChangeLog | 6 ++++++ malloc/arena.c | 10 ++++------ 2 files changed, 10 insertions(+), 6 deletions(-) #diff --git a/ChangeLog b/ChangeLog #index c048c1a..618515e 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. #+ # 2016-08-17 Florian Weimer <fweimer@redhat.com> # # [BZ #20452] diff --git a/malloc/arena.c b/malloc/arena.c index 7c52633..5350992 100644 --- a/malloc/arena.c +++ b/malloc/arena.c @@ -938,14 +938,12 @@ 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); -- 2.10.2