On 8/17/23 17:58, Kees Cook wrote:
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 sa11x0_dma_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: dmaengine@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Thanks
--
Gustavo
---
drivers/dma/sa11x0-dma.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/sa11x0-dma.c b/drivers/dma/sa11x0-dma.c
index a29c13cae716..e5849622f198 100644
--- a/drivers/dma/sa11x0-dma.c
+++ b/drivers/dma/sa11x0-dma.c
@@ -78,7 +78,7 @@ struct sa11x0_dma_desc {
bool cyclic;
unsigned sglen;
- struct sa11x0_dma_sg sg[];
+ struct sa11x0_dma_sg sg[] __counted_by(sglen);
};
struct sa11x0_dma_phy;
@@ -558,6 +558,7 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", &c->vc);
return NULL;
}
+ txd->sglen = j;
j = 0;
for_each_sg(sg, sgent, sglen, i) {
@@ -593,7 +594,6 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
txd->ddar = c->ddar;
txd->size = size;
- txd->sglen = j;
dev_dbg(chan->device->dev, "vchan %p: txd %p: size %zu nr %u\n",
&c->vc, &txd->vd, txd->size, txd->sglen);
@@ -628,6 +628,7 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_dma_cyclic(
dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", &c->vc);
return NULL;
}
+ txd->sglen = sglen;
for (i = k = 0; i < size / period; i++) {
size_t tlen, len = period;
@@ -653,7 +654,6 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_dma_cyclic(
txd->ddar = c->ddar;
txd->size = size;
- txd->sglen = sglen;
txd->cyclic = 1;
txd->period = sgperiod;
