From: Timo Sirainen <timo.sirainen@dovecot.fi>
Date: Mon, 27 Nov 2017 13:17:52 +0000 (+0200)
Subject: lib: mempool-alloconly - Cleanly fail allocations just below SSIZE_T_MAX
X-Git-Tag: 2.3.0.rc1~327
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e4a7dbe5e02280e561d9ac438326ed70700cd39b;p=thirdparty%2Fdovecot%2Fcore.git

lib: mempool-alloconly - Cleanly fail allocations just below SSIZE_T_MAX

Previously it would have assert-crashed in nearest_power().
---

diff --git a/src/lib/mempool-alloconly.c b/src/lib/mempool-alloconly.c
index 66ba6bfcc2..ab8c37b3c6 100644
--- a/src/lib/mempool-alloconly.c
+++ b/src/lib/mempool-alloconly.c
@@ -5,8 +5,12 @@
 #include "safe-memset.h"
 #include "mempool.h"
 
-
-#define MAX_ALLOC_SIZE SSIZE_T_MAX
+#ifndef DEBUG
+#  define POOL_ALLOCONLY_MAX_EXTRA MEM_ALIGN(1)
+#else
+#  define POOL_ALLOCONLY_MAX_EXTRA \
+	(MEM_ALIGN(sizeof(size_t)) + MEM_ALIGN(1) + MEM_ALIGN(SENTRY_COUNT))
+#endif
 
 struct alloconly_pool {
 	struct pool pool;
@@ -260,7 +264,7 @@ static void *pool_alloconly_malloc(pool_t pool, size_t size)
 	void *mem;
 	size_t alloc_size;
 
-	if (unlikely(size == 0 || size > SSIZE_T_MAX))
+	if (unlikely(size == 0 || size > SSIZE_T_MAX - POOL_ALLOCONLY_MAX_EXTRA))
 		i_panic("Trying to allocate %"PRIuSIZE_T" bytes", size);
 
 #ifndef DEBUG
@@ -328,7 +332,7 @@ static void *pool_alloconly_realloc(pool_t pool, void *mem,
 	struct alloconly_pool *apool = (struct alloconly_pool *)pool;
 	unsigned char *new_mem;
 
-	if (unlikely(new_size == 0 || new_size > SSIZE_T_MAX))
+	if (unlikely(new_size == 0 || new_size > SSIZE_T_MAX - POOL_ALLOCONLY_MAX_EXTRA))
 		i_panic("Trying to allocate %"PRIuSIZE_T" bytes", new_size);
 
 	if (mem == NULL)