[PATCH 18/21] dmaengine: ti: omap-dma: Annotate struct omap_desc with __counted_by

Kees Cook
2023-08-18T00:09:44Z

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 omap_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@kernel.org>
Cc: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Cc: dmaengine@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/dma/ti/omap-dma.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/ti/omap-dma.c b/drivers/dma/ti/omap-dma.c
index cf96cf915c0c..11ac3fc0a52a 100644
--- a/drivers/dma/ti/omap-dma.c
+++ b/drivers/dma/ti/omap-dma.c
@@ -124,7 +124,7 @@ struct omap_desc {
uint32_t csdp; /* CSDP value */

unsigned sglen;
- struct omap_sg sg[];
+ struct omap_sg sg[] __counted_by(sglen);
};

enum {
@@ -1005,6 +1005,7 @@ static struct dma_async_tx_descriptor *omap_dma_prep_slave_sg(
d = kzalloc(struct_size(d, sg, sglen), GFP_ATOMIC);
if (!d)
return NULL;
+ d->sglen = sglen;

d->dir = dir;
d->dev_addr = dev_addr;
@@ -1120,8 +1121,6 @@ static struct dma_async_tx_descriptor *omap_dma_prep_slave_sg(
}
}

- d->sglen = sglen;
-
/* Release the dma_pool entries if one allocation failed */
if (ll_failed) {
for (i = 0; i < d->sglen; i++) {
--
2.34.1