Commit 937e79c6 authored Oct 20, 2021 by Arnd Bergmann Committed by Kalle Valo Oct 25, 2021

ath10k: fix invalid dma_addr_t token assignment



Using a kernel pointer in place of a dma_addr_t token can
lead to undefined behavior if that makes it into cache
management functions. The compiler caught one such attempt
in a cast:

drivers/net/wireless/ath/ath10k/mac.c: In function 'ath10k_add_interface':
drivers/net/wireless/ath/ath10k/mac.c:5586:47: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
 5586 |                         arvif->beacon_paddr = (dma_addr_t)arvif->beacon_buf;
      |                                               ^

Looking through how this gets used down the way, I'm fairly
sure that beacon_paddr is never accessed again for ATH10K_DEV_TYPE_HL
devices, and if it was accessed, that would be a bug.

Change the assignment to use a known-invalid address token
instead, which avoids the warning and makes it easier to catch
bugs if it does end up getting used.

Fixes: e263bdab ("ath10k: high latency fixes for beacon buffer")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211014075153.3655910-1-arnd@kernel.org

parent 734223d7

drivers/net/wireless/ath/ath10k/mac.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -5583,7 +5583,15 @@ static int ath10k_add_interface(struct ieee80211_hw *hw,
		if (ar->bus_param.dev_type == ATH10K_DEV_TYPE_HL) {
		arvif->beacon_buf = kmalloc(IEEE80211_MAX_FRAME_LEN,
		GFP_KERNEL);
		arvif->beacon_paddr = (dma_addr_t)arvif->beacon_buf;

		/* Using a kernel pointer in place of a dma_addr_t
		* token can lead to undefined behavior if that
		* makes it into cache management functions. Use a
		* known-invalid address token instead, which
		* avoids the warning and makes it easier to catch
		* bugs if it does end up getting used.
		*/
		arvif->beacon_paddr = DMA_MAPPING_ERROR;
		} else {
		arvif->beacon_buf =
		dma_alloc_coherent(ar->dev,