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Diffstat (limited to 'include/trace/ftrace.h')
-rw-r--r--include/trace/ftrace.h15
1 files changed, 13 insertions, 2 deletions
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 7fb16d90e7b1..f64fbaae781a 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -637,12 +637,20 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* pc = preempt_count();
*
* __data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
- * __entry_size = __data_size + sizeof(*entry);
+ *
+ * // Below we want to get the aligned size by taking into account
+ * // the u32 field that will later store the buffer size
+ * __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),
+ * sizeof(u64));
+ * __entry_size -= sizeof(u32);
*
* do {
* char raw_data[__entry_size]; <- allocate our sample in the stack
* struct trace_entry *ent;
*
+ * zero dead bytes from alignment to avoid stack leak to userspace:
+ *
+ * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
* entry = (struct ftrace_raw_<call> *)raw_data;
* ent = &entry->ent;
* tracing_generic_entry_update(ent, irq_flags, pc);
@@ -685,12 +693,15 @@ static void ftrace_profile_##call(proto) \
pc = preempt_count(); \
\
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
- __entry_size = ALIGN(__data_size + sizeof(*entry), sizeof(u64));\
+ __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\
+ sizeof(u64)); \
+ __entry_size -= sizeof(u32); \
\
do { \
char raw_data[__entry_size]; \
struct trace_entry *ent; \
\
+ *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
entry = (struct ftrace_raw_##call *)raw_data; \
ent = &entry->ent; \
tracing_generic_entry_update(ent, irq_flags, pc); \