From: Nathan Chancellor <nathan@kernel.org> To: richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net Cc: ndesaulniers@google.com, trix@redhat.com, linux-um@lists.infradead.org, llvm@lists.linux.dev, patches@lists.linux.dev, kernel test robot <lkp@intel.com>, Nathan Chancellor <nathan@kernel.org> Subject: [PATCH] um: net: Fix return type of uml_net_start_xmit() Date: Tue, 03 Oct 2023 11:35:53 -0700 [thread overview] Message-ID: <20231003-um-net-wifpts-v1-1-02888c634ee7@kernel.org> (raw) With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. A warning in clang aims to catch these at compile time, which reveals: arch/um/drivers/net_kern.c:353:21: warning: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Wincompatible-function-pointer-types-strict] 353 | .ndo_start_xmit = uml_net_start_xmit, | ^~~~~~~~~~~~~~~~~~ 1 warning generated. ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of 'netdev_tx_t', not 'int'. Adjust the return type of uml_net_start_xmit() to match the prototype's to resolve the warning. While UML does not currently implement support for kCFI, it could in the future, which means this warning becomes a fatal CFI failure at run time. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202310031340.v1vPh207-lkp@intel.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- arch/um/drivers/net_kern.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c index 3d7836c46507..cabcc501b448 100644 --- a/arch/um/drivers/net_kern.c +++ b/arch/um/drivers/net_kern.c @@ -204,7 +204,7 @@ static int uml_net_close(struct net_device *dev) return 0; } -static int uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev) +static netdev_tx_t uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct uml_net_private *lp = netdev_priv(dev); unsigned long flags; --- base-commit: 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa change-id: 20231003-um-net-wifpts-14a7429c7524 Best regards, -- Nathan Chancellor <nathan@kernel.org> _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org> To: richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net Cc: ndesaulniers@google.com, trix@redhat.com, linux-um@lists.infradead.org, llvm@lists.linux.dev, patches@lists.linux.dev, kernel test robot <lkp@intel.com>, Nathan Chancellor <nathan@kernel.org> Subject: [PATCH] um: net: Fix return type of uml_net_start_xmit() Date: Tue, 03 Oct 2023 11:35:53 -0700 [thread overview] Message-ID: <20231003-um-net-wifpts-v1-1-02888c634ee7@kernel.org> (raw) With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. A warning in clang aims to catch these at compile time, which reveals: arch/um/drivers/net_kern.c:353:21: warning: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Wincompatible-function-pointer-types-strict] 353 | .ndo_start_xmit = uml_net_start_xmit, | ^~~~~~~~~~~~~~~~~~ 1 warning generated. ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of 'netdev_tx_t', not 'int'. Adjust the return type of uml_net_start_xmit() to match the prototype's to resolve the warning. While UML does not currently implement support for kCFI, it could in the future, which means this warning becomes a fatal CFI failure at run time. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202310031340.v1vPh207-lkp@intel.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- arch/um/drivers/net_kern.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c index 3d7836c46507..cabcc501b448 100644 --- a/arch/um/drivers/net_kern.c +++ b/arch/um/drivers/net_kern.c @@ -204,7 +204,7 @@ static int uml_net_close(struct net_device *dev) return 0; } -static int uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev) +static netdev_tx_t uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct uml_net_private *lp = netdev_priv(dev); unsigned long flags; --- base-commit: 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa change-id: 20231003-um-net-wifpts-14a7429c7524 Best regards, -- Nathan Chancellor <nathan@kernel.org>
next reply other threads:[~2023-10-03 18:36 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-10-03 18:35 Nathan Chancellor [this message] 2023-10-03 18:35 ` [PATCH] um: net: Fix return type of uml_net_start_xmit() Nathan Chancellor 2023-12-05 17:53 ` Nathan Chancellor 2023-12-06 7:19 ` Anton Ivanov 2023-12-06 16:52 ` Nathan Chancellor
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