From 937e79c67740d1d84736730d679f3cb2552f990e Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 20 Oct 2021 11:59:07 +0300 Subject: [PATCH] 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: e263bdab9c0e ("ath10k: high latency fixes for beacon buffer") Signed-off-by: Arnd Bergmann Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20211014075153.3655910-1-arnd@kernel.org --- drivers/net/wireless/ath/ath10k/mac.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c index 5ec19d9..1f73fbf 100644 --- a/drivers/net/wireless/ath/ath10k/mac.c +++ b/drivers/net/wireless/ath/ath10k/mac.c @@ -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, -- 2.7.4