kernel test robot reported a -Wstringop-truncation warning after I
extend task comm from 16 to 24. Below is the detailed warning:
fs/binfmt_elf.c: In function 'fill_psinfo.isra':
>> fs/binfmt_elf.c:1575:9: warning: 'strncpy' output may be truncated copying 16 bytes from a string of length 23 [-Wstringop-truncation]
1575 | strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Replacing the open-coded strncpy() with the helper get_task_comm() can
avoid this warning.
As the struct prpsinfo is externally parsed, for example by the crash
utility, we can't change the size of pr_fname. So I just leave it as-is.
I also verfied if it still work well when I extend the comm size to 24.
struct elf_prpsinfo is used to dump the task information in userspace
coredump or kernel vmcore. Below is the verfication of vmcore,
crash> ps
PID PPID CPU TASK ST %MEM VSZ RSS COMM
0 0 0 ffffffff9d21a940 RU 0.0 0 0 [swapper/0]
> 0 0 1 ffffa09e40f85e80 RU 0.0 0 0 [swapper/1]
> 0 0 2 ffffa09e40f81f80 RU 0.0 0 0 [swapper/2]
> 0 0 3 ffffa09e40f83f00 RU 0.0 0 0 [swapper/3]
> 0 0 4 ffffa09e40f80000 RU 0.0 0 0 [swapper/4]
> 0 0 5 ffffa09e40f89f80 RU 0.0 0 0 [swapper/5]
0 0 6 ffffa09e40f8bf00 RU 0.0 0 0 [swapper/6]
> 0 0 7 ffffa09e40f88000 RU 0.0 0 0 [swapper/7]
> 0 0 8 ffffa09e40f8de80 RU 0.0 0 0 [swapper/8]
> 0 0 9 ffffa09e40f95e80 RU 0.0 0 0 [swapper/9]
> 0 0 10 ffffa09e40f91f80 RU 0.0 0 0 [swapper/10]
> 0 0 11 ffffa09e40f93f00 RU 0.0 0 0 [swapper/11]
> 0 0 12 ffffa09e40f90000 RU 0.0 0 0 [swapper/12]
> 0 0 13 ffffa09e40f9bf00 RU 0.0 0 0 [swapper/13]
> 0 0 14 ffffa09e40f98000 RU 0.0 0 0 [swapper/14]
> 0 0 15 ffffa09e40f9de80 RU 0.0 0 0 [swapper/15]
It works well as expected.
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@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>
---
fs/binfmt_elf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a813b70f594e..138956fd4a88 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1572,7 +1572,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid));
SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
rcu_read_unlock();
- strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
+ get_task_comm(psinfo->pr_fname, p);
return 0;
}
--
2.17.1
