[PATCH][next] wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()

[PATCH][next] wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()

[Gustavo A. R. Silva]

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).

Also, relocate `event->datalen = datalen;` to before calling
`memcpy(event->data, data, datalen);`, so that the __counted_by
annotation has effect, and flex-array member `data` can be properly
bounds-checked at run-time.

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/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
index dac7eb77799b..68960ae98987 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
@@ -33,7 +33,7 @@ struct brcmf_fweh_queue_item {
 	u8 ifaddr[ETH_ALEN];
 	struct brcmf_event_msg_be emsg;
 	u32 datalen;
-	u8 data[];
+	u8 data[] __counted_by(datalen);
 };
 
 /*
@@ -418,17 +418,17 @@ void brcmf_fweh_process_event(struct brcmf_pub *drvr,
 	    datalen + sizeof(*event_packet) > packet_len)
 		return;
 
-	event = kzalloc(sizeof(*event) + datalen, gfp);
+	event = kzalloc(struct_size(event, data, datalen), gfp);
 	if (!event)
 		return;
 
+	event->datalen = datalen;
 	event->code = code;
 	event->ifidx = event_packet->msg.ifidx;
 
 	/* use memcpy to get aligned event message */
 	memcpy(&event->emsg, &event_packet->msg, sizeof(event->emsg));
 	memcpy(event->data, data, datalen);
-	event->datalen = datalen;
 	memcpy(event->ifaddr, event_packet->eth.h_dest, ETH_ALEN);
 
 	brcmf_fweh_queue_event(fweh, event);
-- 
2.34.1

Re: [PATCH][next] wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()

[Kees Cook]

On Mon, Oct 09, 2023 at 03:42:04PM -0600, Gustavo A. R. Silva 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 via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> Also, relocate `event->datalen = datalen;` to before calling
> `memcpy(event->data, data, datalen);`, so that the __counted_by
> annotation has effect, and flex-array member `data` can be properly
> bounds-checked at run-time.
> 
> 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>

Yeah, looks right. Thanks for moving the count assignment.

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
> index dac7eb77799b..68960ae98987 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c
> @@ -33,7 +33,7 @@ struct brcmf_fweh_queue_item {
>  	u8 ifaddr[ETH_ALEN];
>  	struct brcmf_event_msg_be emsg;
>  	u32 datalen;
> -	u8 data[];
> +	u8 data[] __counted_by(datalen);
>  };
>  
>  /*
> @@ -418,17 +418,17 @@ void brcmf_fweh_process_event(struct brcmf_pub *drvr,
>  	    datalen + sizeof(*event_packet) > packet_len)
>  		return;
>  
> -	event = kzalloc(sizeof(*event) + datalen, gfp);
> +	event = kzalloc(struct_size(event, data, datalen), gfp);
>  	if (!event)
>  		return;
>  
> +	event->datalen = datalen;
>  	event->code = code;
>  	event->ifidx = event_packet->msg.ifidx;
>  
>  	/* use memcpy to get aligned event message */
>  	memcpy(&event->emsg, &event_packet->msg, sizeof(event->emsg));
>  	memcpy(event->data, data, datalen);
> -	event->datalen = datalen;
>  	memcpy(event->ifaddr, event_packet->eth.h_dest, ETH_ALEN);
>  
>  	brcmf_fweh_queue_event(fweh, event);
> -- 
> 2.34.1
> 
> 

-- 
Kees Cook

Re: [PATCH][next] wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()

[Arend Van Spriel]

[-- Attachment #1: Type: text/plain, Size: 1227 bytes --]

On October 9, 2023 11:42:11 PM "Gustavo A. R. Silva" 
<gustavoars@kernel.org> 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 via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> Also, relocate `event->datalen = datalen;` to before calling
> `memcpy(event->data, data, datalen);`, so that the __counted_by
> annotation has effect, and flex-array member `data` can be properly
> bounds-checked at run-time.
>
> 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.

From the description above I think this change looks sane so...

Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
> drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)



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Re: [PATCH][next] wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()

[Kalle Valo]

"Gustavo A. R. Silva" <gustavoars@kernel.org> 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 via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> Also, relocate `event->datalen = datalen;` to before calling
> `memcpy(event->data, data, datalen);`, so that the __counted_by
> annotation has effect, and flex-array member `data` can be properly
> bounds-checked at run-time.
> 
> 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>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>

Patch applied to wireless-next.git, thanks.

62d19b358088 wifi: brcmfmac: fweh: Add __counted_by for struct brcmf_fweh_queue_item and use struct_size()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/ZSRzrIe0345eymk2@work/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches