[PATCH] ath10k: fix pointer arithmetic error in trace call

[PATCH] ath10k: fix pointer arithmetic error in trace call

[Francesco Magliocca]

Reading through the commit history, it looks like
there is no special need why we must skip the first 4 bytes
in this trace call:

trace_ath10k_htt_rx_desc(ar, (void*)rx_desc + sizeof(u32),
			 hw->rx_desc_ops->rx_desc_size - sizeof(u32));

found in the function ath10k_htt_rx_amsdu_pop in the file htt_rx.c

i think the original author
(who is also the one who added rx_desc tracing capabilities
in a0883cf7e75a) just wanted to trace the rx_desc contents,
ignoring the fw_rx_desc_base info field
(which is the part being skipped over).
But the trace_ath10k_htt_rx_desc later added
don't care about skipping it, so it may be good
to uniform this call to the others in the file.
But this would change the output of the trace and
thus it may be a problem for tools that rely on it.
Therefore I propose until further discussion
to just keep it as it is and just fix the pointer arithmetic bug.

Add missing void* cast to rx descriptor pointer in order to
properly skip the initial 4 bytes of the rx descriptor
when passing it to trace_ath10k_htt_rx_desc trace function.

This fixes the pointer arithmetic error detected
by Dan Carpenter's static analysis tool.

Fixes: 6bae9de622d3 ("ath10k: abstract htt_rx_desc structure")

Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00157-QCARMSWPZ-1

Signed-off-by: Francesco Magliocca <franciman12@gmail.com>
Link: https://lore.kernel.org/ath10k/20220201130900.GD22458@kili/
---
 drivers/net/wireless/ath/ath10k/htt_rx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
index 9ad64ca84beb..e01efcd2ce06 100644
--- a/drivers/net/wireless/ath/ath10k/htt_rx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
@@ -429,7 +429,7 @@ static int ath10k_htt_rx_amsdu_pop(struct ath10k_htt *htt,
 				RX_MSDU_END_INFO0_LAST_MSDU;
 
 		/* FIXME: why are we skipping the first part of the rx_desc? */
-		trace_ath10k_htt_rx_desc(ar, rx_desc + sizeof(u32),
+		trace_ath10k_htt_rx_desc(ar, (void*)rx_desc + sizeof(u32),
 					 hw->rx_desc_ops->rx_desc_size - sizeof(u32));
 
 		if (last_msdu)
-- 
2.35.1


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Re: [PATCH] ath10k: fix pointer arithmetic error in trace call

[Kalle Valo]

+ linux-wireless

Francesco Magliocca <franciman12@gmail.com> writes:

> Reading through the commit history, it looks like
> there is no special need why we must skip the first 4 bytes
> in this trace call:
>
> trace_ath10k_htt_rx_desc(ar, (void*)rx_desc + sizeof(u32),
> 			 hw->rx_desc_ops->rx_desc_size - sizeof(u32));
>
> found in the function ath10k_htt_rx_amsdu_pop in the file htt_rx.c
>
> i think the original author
> (who is also the one who added rx_desc tracing capabilities
> in a0883cf7e75a) just wanted to trace the rx_desc contents,
> ignoring the fw_rx_desc_base info field
> (which is the part being skipped over).
> But the trace_ath10k_htt_rx_desc later added
> don't care about skipping it, so it may be good
> to uniform this call to the others in the file.
> But this would change the output of the trace and
> thus it may be a problem for tools that rely on it.
> Therefore I propose until further discussion
> to just keep it as it is and just fix the pointer arithmetic bug.
>
> Add missing void* cast to rx descriptor pointer in order to
> properly skip the initial 4 bytes of the rx descriptor
> when passing it to trace_ath10k_htt_rx_desc trace function.
>
> This fixes the pointer arithmetic error detected
> by Dan Carpenter's static analysis tool.
>
> Fixes: 6bae9de622d3 ("ath10k: abstract htt_rx_desc structure")
>
> Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00157-QCARMSWPZ-1
>
> Signed-off-by: Francesco Magliocca <franciman12@gmail.com>
> Link: https://lore.kernel.org/ath10k/20220201130900.GD22458@kili/

Please submit v2 and CC also linux-wireless, otherwise patchwork won't
see the patch.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

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

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