[12/55] fs/exec: replace strlcpy with strscpy_pad in __set_task_comm

Commit Message

Andrew Morton Jan. 20, 2022, 2:08 a.m. UTC

From: Yafang Shao <[e-mail]>
Subject: fs/exec: replace strlcpy with strscpy_pad in __set_task_comm

Patch series "task comm cleanups", v2.

This patchset is part of the patchset "extend task comm from 16 to 24"[1].
Now we have different opinion that dynamically allocates memory to store
kthread's long name into a separate pointer, so I decide to take the
useful cleanups apart from the original patchset and send it
separately[2].

These useful cleanups can make the usage around task comm less
error-prone.  Furthermore, it will be useful if we want to extend task
comm in the future.

[1]. https://lore.kernel.org/lkml/[e-mail]/
[2]. https://lore.kernel.org/lkml/CALOAHbAx55AUo3bm8ZepZSZnw7A08cvKPdPyNTf=[e-mail]/


This patch (of 7):

strlcpy() can trigger out-of-bound reads on the source string[1], we'd
better use strscpy() instead.  To make it be robust against full tsk->comm
copies that got noticed in other places, we should make sure it's zero
padded.

[1] https://github.com/KSPP/linux/issues/89

Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Yafang Shao <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Reviewed-by: David Hildenbrand <[e-mail]>
Cc: Mathieu Desnoyers <[e-mail]>
Cc: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexei Starovoitov <[e-mail]>
Cc: Andrii Nakryiko <[e-mail]>
Cc: Michal Miroslaw <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Al Viro <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Petr Mladek <[e-mail]>
Cc: Andrii Nakryiko <[e-mail]>
Cc: Dennis Dalessandro <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 fs/exec.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

--- a/fs/exec.c~fs-exec-replace-strlcpy-with-strscpy_pad-in-__set_task_comm
+++ a/fs/exec.c
@@ -1222,7 +1222,7 @@  void __set_task_comm(struct task_struct
 {
 	task_lock(tsk);
 	trace_task_rename(tsk, buf);
-	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
+	strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
 	task_unlock(tsk);
 	perf_event_comm(tsk, exec);
 }