Re: [PATCH] ath10k: fix invalid dma_addr_t token assignment
From: Kalle Valo <hidden>
Date: 2021-10-18 13:10:56
Also in:
linux-wireless, lkml
Arnd Bergmann [off-list ref] writes:
From: Arnd Bergmann <arnd@arndb.de>
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.That's my understanding as well. beacon_paddr is only accessed in ath10k_wmi_event_host_swba() and only low latency (ATH10K_DEV_TYPE_LL) should use that function.
quoted hunk
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 <arnd@arndb.de> --- drivers/net/wireless/ath/ath10k/mac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c index 7ca68c81d9b6..c0e78eaa65f8 100644 --- a/drivers/net/wireless/ath/ath10k/mac.c +++ b/drivers/net/wireless/ath/ath10k/mac.c@@ -5583,7 +5583,7 @@ 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; + arvif->beacon_paddr = DMA_MAPPING_ERROR;
In the pending branch I added a comment here: https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=02a383c9bf959147a95c4efeaa4edf35c4450fac -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches