dovecot-2.2: lib: data-stack - fix incorrect pointer comparison ...

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-2.2/rev/27ceef4cbd10
changeset: 17650:27ceef4cbd10
user:      Phil Carmody <phil at dovecot.fi>
date:      Mon Jul 28 16:45:33 2014 +0300
description:
lib: data-stack - fix incorrect pointer comparison in t_try_realloc in DEBUG builds
When trying to work out if it's a valid realloc, we need to remember
that in DEBUG builds, we have hidden a size value (in a MEM_ALIGNED
space) before the pointer we return.

Signed-off-by: Phil Carmody <phil at dovecot.fi>

diffstat:

 src/lib/data-stack.c |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (24 lines):

diff -r 3856ea7037db -r 27ceef4cbd10 src/lib/data-stack.c
--- a/src/lib/data-stack.c	Mon Jul 28 16:45:33 2014 +0300
+++ b/src/lib/data-stack.c	Mon Jul 28 16:45:33 2014 +0300
@@ -454,7 +454,7 @@
 
 bool t_try_realloc(void *mem, size_t size)
 {
-	size_t last_alloc_size;
+	size_t debug_adjust = 0, last_alloc_size;
 	unsigned char *after_last_alloc;
 
 	if (unlikely(size == 0 || size > SSIZE_T_MAX))
@@ -465,7 +465,10 @@
 
 	/* see if we're trying to grow the memory we allocated last */
 	after_last_alloc = data_stack_after_last_alloc(current_block);
-	if (after_last_alloc - last_alloc_size == mem) {
+#ifdef DEBUG
+	debug_adjust = MEM_ALIGN(sizeof(size_t));
+#endif
+	if (after_last_alloc - last_alloc_size + debug_adjust == mem) {
 		/* yeah, see if we have space to grow */
 		size_t new_alloc_size, alloc_growth;