From: Marco Elver <elver@xxxxxxxxxx>
[ 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@xxxxxxxxxxxx/
Reported-by: Ido Schimmel <idosch@xxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20201125224840.2014773-1-elver@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Stable-dep-of: db0b124f02ba ("igc: Enhance Qbv scheduling by using first flag bit")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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;
}
--
2.35.1
