[dpdk-dev] [PATCH] Correctly handle malloc_elem resize with padding

[Jamie Lavigne <lavignen@amazon.com>]

Currently when a malloc_elem is split after resizing, any padding
present in the elem is ignored.  This causes the resized elem to be too
small when padding is present, and user data can overwrite the beginning
of the following malloc_elem.

Solve this by including the size of the padding when computing where to
split the malloc_elem.

Signed-off-by: Jamie Lavigne <lavignen@amazon.com>
---
 lib/librte_eal/common/malloc_elem.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/librte_eal/common/malloc_elem.c b/lib/librte_eal/common/malloc_elem.c
index 42568e1..2ed1942 100644
--- a/lib/librte_eal/common/malloc_elem.c
+++ b/lib/librte_eal/common/malloc_elem.c
@@ -333,9 +333,11 @@ malloc_elem_resize(struct malloc_elem *elem, size_t size)
 	elem_free_list_remove(next);
 	join_elem(elem, next);
 
-	if (elem->size - new_size >= MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD){
+	const size_t new_total_size = new_size + elem->pad;
+
+	if (elem->size - new_total_size >= MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD){
 		/* now we have a big block together. Lets cut it down a bit, by splitting */
-		struct malloc_elem *split_pt = RTE_PTR_ADD(elem, new_size);
+		struct malloc_elem *split_pt = RTE_PTR_ADD(elem, new_total_size);
 		split_pt = RTE_PTR_ALIGN_CEIL(split_pt, RTE_CACHE_LINE_SIZE);
 		split_elem(elem, split_pt);
 		malloc_elem_free_list_insert(split_pt);
-- 
2.7.3.AMZN