diff mbox series

[v3] dma-buf: Proactively round up to kmalloc bucket size

Message ID 20221018090858.never.941-kees@kernel.org (mailing list archive)
State Mainlined
Commit cd536db050993f7c220a6cfb01de5356032b6f8e
Headers show
Series [v3] dma-buf: Proactively round up to kmalloc bucket size | expand

Commit Message

Kees Cook Oct. 18, 2022, 9:10 a.m. UTC 
Instead of discovering the kmalloc bucket size _after_ allocation, round
up proactively so the allocation is explicitly made for the full size,
allowing the compiler to correctly reason about the resulting size of
the buffer through the existing __alloc_size() hint.

Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v3: added reviewed-by, rebase to v6.1-rc1
v2: https://lore.kernel.org/lkml/20220923202822.2667581-9-keescook@chromium.org/
---
 drivers/dma-buf/dma-resv.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index e3885c90a3ac..1c76aed8e262 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -98,12 +98,17 @@  static void dma_resv_list_set(struct dma_resv_list *list,
 static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
 {
 	struct dma_resv_list *list;
+	size_t size;
 
-	list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL);
+	/* Round up to the next kmalloc bucket size. */
+	size = kmalloc_size_roundup(struct_size(list, table, max_fences));
+
+	list = kmalloc(size, GFP_KERNEL);
 	if (!list)
 		return NULL;
 
-	list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) /
+	/* Given the resulting bucket size, recalculated max_fences. */
+	list->max_fences = (size - offsetof(typeof(*list), table)) /
 		sizeof(*list->table);
 
 	return list;