| Message ID | 20230920202509.never.299-kees@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | sky2: Make sure there is at least one frag_addr available | expand |
On Wed, 20 Sep 2023 13:25:13 -0700 Kees Cook <keescook@chromium.org> wrote: > In the likely pathological case of building sky2 with 16k PAGE_SIZE, > 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 <mlindner@marvell.com> > Cc: Stephen Hemminger <stephen@networkplumber.org> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Eric Dumazet <edumazet@google.com> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Paolo Abeni <pabeni@redhat.com> > Cc: netdev@vger.kernel.org > Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202309191958.UBw1cjXk-lkp@intel.com/ > Signed-off-by: Kees Cook <keescook@chromium.org> > --- With page size of 16K 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 thinking this is some flex array leftover? Or can't figure out that in this case an rx skb with fragments would never be created. The workaround is fine, but could you add an explanatory comment?
From: Kees Cook <keescook@chromium.org> Date: Wed, 20 Sep 2023 13:25:13 -0700 > In the likely pathological case of building sky2 with 16k PAGE_SIZE, > 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 <mlindner@marvell.com> > Cc: Stephen Hemminger <stephen@networkplumber.org> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Eric Dumazet <edumazet@google.com> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Paolo Abeni <pabeni@redhat.com> > Cc: netdev@vger.kernel.org > Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202309191958.UBw1cjXk-lkp@intel.com/ > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com> That "nobody uses this HW on non-x86 systems, why bother" is fun each time. > --- > 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 ddec1627f1a7..8d0bacf4e49c 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 { Thanks, Olek
diff --git a/drivers/net/ethernet/marvell/sky2.h b/drivers/net/ethernet/marvell/sky2.h index ddec1627f1a7..8d0bacf4e49c 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 {
In the likely pathological case of building sky2 with 16k PAGE_SIZE, 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 <mlindner@marvell.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: netdev@vger.kernel.org Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202309191958.UBw1cjXk-lkp@intel.com/ Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/net/ethernet/marvell/sky2.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)