Show a warning if task comm is truncated. Below is the result
of my test case:
truncated kthread comm:I-am-a-kthread-with-a-l (pid:178) by 8 characters
As we have extended task comm to 24, all the existing in-tree
kthreads/workqueues are not truncated anymore. So this warning will only
be printed for the newly introduced one if it has a long name.
Suggested-by: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx>
Cc: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
---
kernel/kthread.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 5b37a8567168..63f38d3a4f62 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -399,12 +399,17 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
if (!IS_ERR(task)) {
static const struct sched_param param = { .sched_priority = 0 };
char name[TASK_COMM_LEN];
+ int len;
/*
* task is already visible to other tasks, so updating
* COMM must be protected.
*/
- vsnprintf(name, sizeof(name), namefmt, args);
+ len = vsnprintf(name, sizeof(name), namefmt, args);
+ if (len >= TASK_COMM_LEN) {
+ pr_warn("truncated kthread comm:%s (pid:%d) by %d characters\n",
+ name, task->pid, len - TASK_COMM_LEN + 1);
+ }
set_task_comm(task, name);
/*
* root may have changed our (kthreadd's) priority or CPU mask.
--
2.17.1
