Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). As found with Coccinelle[1], add __counted_by for struct axi_dmac_desc. Additionally, since the element count member must be set before accessing the annotated flexible array member, move its initialization earlier. [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci Cc: Vinod Koul <vkoul@xxxxxxxxxx> Cc: Lars-Peter Clausen <lars@xxxxxxxxxx> Cc: dmaengine@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- drivers/dma/dma-axi-dmac.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c index fc7cdad37161..b9f85cb20d3e 100644 --- a/drivers/dma/dma-axi-dmac.c +++ b/drivers/dma/dma-axi-dmac.c @@ -117,7 +117,7 @@ struct axi_dmac_desc { unsigned int num_submitted; unsigned int num_completed; unsigned int num_sgs; - struct axi_dmac_sg sg[]; + struct axi_dmac_sg sg[] __counted_by(num_sgs); }; struct axi_dmac_chan { @@ -484,12 +484,11 @@ static struct axi_dmac_desc *axi_dmac_alloc_desc(unsigned int num_sgs) desc = kzalloc(struct_size(desc, sg, num_sgs), GFP_NOWAIT); if (!desc) return NULL; + desc->num_sgs = num_sgs; for (i = 0; i < num_sgs; i++) desc->sg[i].id = AXI_DMAC_SG_UNUSED; - desc->num_sgs = num_sgs; - return desc; } -- 2.34.1
