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

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 <[email protected]>

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

drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c +3 -3

index dac7eb77799b..68960ae98987 100644
@@ -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);

Signature · 1 line

2.34.1

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 <[email protected]>

---
drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c | 6 +++---

1 file changed, 3 insertions(+), 3 deletions(-)

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 <[email protected]>

Reviewed-by Kees Cook <[email protected]>

Acked-by Arend van Spriel <[email protected]>