[PATCH][next] soc: qcom: apr: Add __counted_by for struct apr_rx_buf and use struct_size()

Gustavo A. R. Silva
2023-10-09T21:30:27Z

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 via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

While there, use struct_size() helper, instead of the open-coded
version, to calculate the size for the allocation of the whole
flexible structure, including of course, the flexible-array member.

This code was found with the help of Coccinelle, and audited and
fixed manually.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/soc/qcom/apr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/apr.c b/drivers/soc/qcom/apr.c
index 30f81d6d9d9d..1f8b315576a4 100644
--- a/drivers/soc/qcom/apr.c
+++ b/drivers/soc/qcom/apr.c
@@ -41,7 +41,7 @@ struct packet_router {
struct apr_rx_buf {
struct list_head node;
int len;
- uint8_t buf[];
+ uint8_t buf[] __counted_by(len);
};

/**
@@ -171,7 +171,7 @@ static int apr_callback(struct rpmsg_device *rpdev, void *buf,
return -EINVAL;
}

- abuf = kzalloc(sizeof(*abuf) + len, GFP_ATOMIC);
+ abuf = kzalloc(struct_size(abuf, buf, len), GFP_ATOMIC);
if (!abuf)
return -ENOMEM;

--
2.34.1