tracing: Use strncpy instead of memcpy when copying comm in trace.c

tzanussi · rostedt · commit 85f726a35e50 · 2019-03-05T12:14:42.000-05:00
Because there may be random garbage beyond a string's null terminator, code that might use the entire comm array e.g. histogram keys, can give unexpected results if that garbage is copied in too, so avoid that possibility by using strncpy instead of memcpy. Link: http://lkml.kernel.org/r/1d6ebac26570c2a29ce9fb575379f17ef5c8b81b.1551802084.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
@@ -1497,7 +1497,7 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 	max_data->critical_start = data->critical_start;
 	max_data->critical_end = data->critical_end;
 
-	memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
+	strncpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
 	max_data->pid = tsk->pid;
 	/*
 	 * If tsk == current, then use current_uid(), as that does not use
@@ -1923,7 +1923,7 @@ static inline char *get_saved_cmdlines(int idx)
 
 static inline void set_cmdline(int idx, const char *cmdline)
 {
-	memcpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN);
+	strncpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN);
 }
 
 static int allocate_cmdlines_buffer(unsigned int val,

Original file line number	Diff line number	Diff line change
`@@ -1497,7 +1497,7 @@ __update_max_tr(struct trace_array tr, struct task_struct tsk, int cpu)`
`1497`	`1497`	`max_data->critical_start = data->critical_start;`
`1498`	`1498`	`max_data->critical_end = data->critical_end;`
`1499`	`1499`
`1500`		`- memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);`
	`1500`	`+ strncpy(max_data->comm, tsk->comm, TASK_COMM_LEN);`
`1501`	`1501`	`max_data->pid = tsk->pid;`
`1502`	`1502`	`/*`
`1503`	`1503`	`* If tsk == current, then use current_uid(), as that does not use`
`@@ -1923,7 +1923,7 @@ static inline char *get_saved_cmdlines(int idx)`
`1923`	`1923`
`1924`	`1924`	`static inline void set_cmdline(int idx, const char *cmdline)`
`1925`	`1925`	`{`
`1926`		`- memcpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN);`
	`1926`	`+ strncpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN);`
`1927`	`1927`	`}`
`1928`	`1928`
`1929`	`1929`	`static int allocate_cmdlines_buffer(unsigned int val,`