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));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This patch can fix this warning.
Replacing strncpy() with strscpy_pad() can avoid this warning.
This patch also replace the hard-coded 16 with TASK_COMM_LEN to make it
more compatible with task comm size change.
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>
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 +-
include/linux/elfcore-compat.h | 3 ++-
include/linux/elfcore.h | 4 ++--
3 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a813b70f594e..a4ba79fce2a9 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));
+ strscpy_pad(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
return 0;
}
diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h
index e272c3d452ce..afa0eb45196b 100644
--- a/include/linux/elfcore-compat.h
+++ b/include/linux/elfcore-compat.h
@@ -5,6 +5,7 @@
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/compat.h>
+#include <linux/sched.h>
/*
* Make sure these layouts match the linux/elfcore.h native definitions.
@@ -43,7 +44,7 @@ struct compat_elf_prpsinfo
__compat_uid_t pr_uid;
__compat_gid_t pr_gid;
compat_pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid;
- char pr_fname[16];
+ char pr_fname[TASK_COMM_LEN];
char pr_psargs[ELF_PRARGSZ];
};
diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index 2aaa15779d50..8d79cd58b09a 100644
--- a/include/linux/elfcore.h
+++ b/include/linux/elfcore.h
@@ -65,8 +65,8 @@ struct elf_prpsinfo
__kernel_gid_t pr_gid;
pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid;
/* Lots missing */
- char pr_fname[16]; /* filename of executable */
- char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
+ char pr_fname[TASK_COMM_LEN]; /* filename of executable */
+ char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
};
static inline void elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs)
--
2.17.1
