于 18/3/28 下午11:44, Steven Rostedt 写道:
On Wed, 28 Mar 2018 11:35:22 -0400
Steven Rostedt <[email protected]> wrote:
On Wed, 28 Mar 2018 20:32:27 +0800
Wang Yu <[email protected]> wrote:
when pid is bigger than PID_MAX_DEFAULT, the comm of task
is <...>, it is better use pid_max to compare
Signed-off-by: Wang Yu <[email protected]>
---
kernel/trace/trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
mode change 100644 => 100755 kernel/trace/trace.c
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
old mode 100644
new mode 100755
index 20a2300..0d4bc7a
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1976,7 +1976,7 @@ static void __trace_find_cmdline(int pid, char comm[])
return;
}
- if (pid > PID_MAX_DEFAULT) {
+ if (pid > pid_max) {
Thanks! this probably should go to stable.
I take that back. This patch can cause a buffer overflow access.
If you looked at the line after this check, you would see:
if (pid > PID_MAX_DEFAULT) {
strcpy(comm, "<...>");
return;
}
map = savedcmd->map_pid_to_cmdline[pid];
And if you looked to see what map_pid_to_cmdline is:
struct saved_cmdlines_buffer {
unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
Your patch will access memory past the end of that array, and cause a
bug.
If you want to support more than PID_MAX_DEFAULT, a lot more needs to
change than this. And a change like this isn't going to go to stable.
What you can do is make that map_pid_to_cmdline array bigger.
-- Steve
I am sorry about it, and as the number of cpu cores increases, the current
PID_MAX_DEFAULT is too small, our online machines set the pid_max 65536 as
default, so the task
pid number bigger than PID_MAX_DEFAULT can't show the real comm (only <...>),
so i want to
ajust the PID_MAX_DEFAULT upto 4x, and what do you think?
* This controls the default maximum pid allocated to a process
*/
-#define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)
+#define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x20000)
-- Steve
strcpy(comm, "<...>");
return;
}
