From 21f85b026dfec532b27012e65ee4ba5645b88708 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 22 Sep 2023 09:50:39 -0700 Subject: [PATCH] sky2: Make sure there is at least one frag_addr available [ Upstream commit 6a70e5cbedaf8ad10528ac9ac114f3ec20f422df ] In the pathological case of building sky2 with 16k PAGE_SIZE, the frag_addr[] array would never be used, so the original code was correct that size should be 0. But the compiler now gets upset with 0 size arrays in places where it hasn't eliminated the code that might access such an array (it can't figure out that in this case an rx skb with fragments would never be created). To keep the compiler happy, make sure there is at least 1 frag_addr in struct rx_ring_info: In file included from include/linux/skbuff.h:28, from include/net/net_namespace.h:43, from include/linux/netdevice.h:38, from drivers/net/ethernet/marvell/sky2.c:18: drivers/net/ethernet/marvell/sky2.c: In function 'sky2_rx_unmap_skb': include/linux/dma-mapping.h:416:36: warning: array subscript i is outside array bounds of 'dma_addr_t[0]' {aka 'long long unsigned int[]'} [-Warray-bounds=] 416 | #define dma_unmap_page(d, a, s, r) dma_unmap_page_attrs(d, a, s, r, 0) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/ethernet/marvell/sky2.c:1257:17: note: in expansion of macro 'dma_unmap_page' 1257 | dma_unmap_page(&pdev->dev, re->frag_addr[i], | ^~~~~~~~~~~~~~ In file included from drivers/net/ethernet/marvell/sky2.c:41: drivers/net/ethernet/marvell/sky2.h:2198:25: note: while referencing 'frag_addr' 2198 | dma_addr_t frag_addr[ETH_JUMBO_MTU >> PAGE_SHIFT]; | ^~~~~~~~~ With CONFIG_PAGE_SIZE_16KB=y, PAGE_SHIFT == 14, so: #define ETH_JUMBO_MTU 9000 causes "ETH_JUMBO_MTU >> PAGE_SHIFT" to be 0. Use "?: 1" to solve this build warning. Cc: Mirko Lindner Cc: Stephen Hemminger Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: netdev@vger.kernel.org Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202309191958.UBw1cjXk-lkp@intel.com/ Reviewed-by: Alexander Lobakin Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/ethernet/marvell/sky2.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/marvell/sky2.h b/drivers/net/ethernet/marvell/sky2.h index b2dddd8a246c..2bd0a7971ae6 100644 --- a/drivers/net/ethernet/marvell/sky2.h +++ b/drivers/net/ethernet/marvell/sky2.h @@ -2195,7 +2195,7 @@ struct rx_ring_info { struct sk_buff *skb; dma_addr_t data_addr; DEFINE_DMA_UNMAP_LEN(data_size); - dma_addr_t frag_addr[ETH_JUMBO_MTU >> PAGE_SHIFT]; + dma_addr_t frag_addr[ETH_JUMBO_MTU >> PAGE_SHIFT ?: 1]; }; enum flow_control {