From: Marco Elver elver@google.com
[ Upstream commit fa69ee5aa48b5b52e8028c2eb486906e9998d081 ]
It turns out that usage of skb extensions can cause memory leaks. Ido Schimmel reported: "[...] there are instances that blindly overwrite 'skb->extensions' by invoking skb_copy_header() after __alloc_skb()."
Therefore, give up on using skb extensions for KCOV handle, and instead directly store kcov_handle in sk_buff.
Fixes: 6370cc3bbd8a ("net: add kcov handle to skb extensions") Fixes: 85ce50d337d1 ("net: kcov: don't select SKB_EXTENSIONS when there is no NET") Fixes: 97f53a08cba1 ("net: linux/skbuff.h: combine SKB_EXTENSIONS + KCOV handling") Link: https://lore.kernel.org/linux-wireless/20201121160941.GA485907@shredder.lan/ Reported-by: Ido Schimmel idosch@idosch.org Signed-off-by: Marco Elver elver@google.com Link: https://lore.kernel.org/r/20201125224840.2014773-1-elver@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Stable-dep-of: db0b124f02ba ("igc: Enhance Qbv scheduling by using first flag bit") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/skbuff.h | 37 +++++++++++++------------------------ lib/Kconfig.debug | 1 - net/core/skbuff.c | 6 ------ 3 files changed, 13 insertions(+), 31 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 462b0e3ef2b2..521d66ec8d80 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -702,6 +702,7 @@ typedef unsigned char *sk_buff_data_t; * @transport_header: Transport layer header * @network_header: Network layer header * @mac_header: Link layer header + * @kcov_handle: KCOV remote handle for remote coverage collection * @tail: Tail pointer * @end: End pointer * @head: Head of buffer @@ -906,6 +907,10 @@ struct sk_buff { __u16 network_header; __u16 mac_header;
+#ifdef CONFIG_KCOV + u64 kcov_handle; +#endif + /* private: */ __u32 headers_end[0]; /* public: */ @@ -4160,9 +4165,6 @@ enum skb_ext_id { #endif #if IS_ENABLED(CONFIG_MPTCP) SKB_EXT_MPTCP, -#endif -#if IS_ENABLED(CONFIG_KCOV) - SKB_EXT_KCOV_HANDLE, #endif SKB_EXT_NUM, /* must be last */ }; @@ -4618,35 +4620,22 @@ static inline void skb_reset_redirect(struct sk_buff *skb) #endif }
-#if IS_ENABLED(CONFIG_KCOV) && IS_ENABLED(CONFIG_SKB_EXTENSIONS) static inline void skb_set_kcov_handle(struct sk_buff *skb, const u64 kcov_handle) { - /* Do not allocate skb extensions only to set kcov_handle to zero - * (as it is zero by default). However, if the extensions are - * already allocated, update kcov_handle anyway since - * skb_set_kcov_handle can be called to zero a previously set - * value. - */ - if (skb_has_extensions(skb) || kcov_handle) { - u64 *kcov_handle_ptr = skb_ext_add(skb, SKB_EXT_KCOV_HANDLE); - - if (kcov_handle_ptr) - *kcov_handle_ptr = kcov_handle; - } +#ifdef CONFIG_KCOV + skb->kcov_handle = kcov_handle; +#endif }
static inline u64 skb_get_kcov_handle(struct sk_buff *skb) { - u64 *kcov_handle = skb_ext_find(skb, SKB_EXT_KCOV_HANDLE); - - return kcov_handle ? *kcov_handle : 0; -} +#ifdef CONFIG_KCOV + return skb->kcov_handle; #else -static inline void skb_set_kcov_handle(struct sk_buff *skb, - const u64 kcov_handle) { } -static inline u64 skb_get_kcov_handle(struct sk_buff *skb) { return 0; } -#endif /* CONFIG_KCOV && CONFIG_SKB_EXTENSIONS */ + return 0; +#endif +}
#endif /* __KERNEL__ */ #endif /* _LINUX_SKBUFF_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 4aed8abb2022..19c28a34c5f1 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1915,7 +1915,6 @@ config KCOV depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS select DEBUG_FS select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC - select SKB_EXTENSIONS if NET help KCOV exposes kernel code coverage information in a form suitable for coverage-guided fuzzing (randomized testing). diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 06169889b0ca..176bcbb07aab 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4258,9 +4258,6 @@ static const u8 skb_ext_type_len[] = { #if IS_ENABLED(CONFIG_MPTCP) [SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext), #endif -#if IS_ENABLED(CONFIG_KCOV) - [SKB_EXT_KCOV_HANDLE] = SKB_EXT_CHUNKSIZEOF(u64), -#endif };
static __always_inline unsigned int skb_ext_total_length(void) @@ -4277,9 +4274,6 @@ static __always_inline unsigned int skb_ext_total_length(void) #endif #if IS_ENABLED(CONFIG_MPTCP) skb_ext_type_len[SKB_EXT_MPTCP] + -#endif -#if IS_ENABLED(CONFIG_KCOV) - skb_ext_type_len[SKB_EXT_KCOV_HANDLE] + #endif 0; }