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From: Yafang Shao <laoar.shao@gmail.com>
To: keescook@chromium.org, rostedt@goodmis.org,
	mathieu.desnoyers@efficios.com, arnaldo.melo@gmail.com,
	pmladek@suse.com, peterz@infradead.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org, valentin.schneider@arm.com,
	qiang.zhang@windriver.com, robdclark@chromium.org,
	christian@brauner.io, dietmar.eggemann@arm.com, mingo@redhat.com,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	davem@davemloft.net, kuba@kernel.org, ast@kernel.org,
	daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com,
	songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com,
	kpsingh@kernel.org
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, oliver.sang@intel.com,
	lkp@intel.com, Yafang Shao <laoar.shao@gmail.com>
Subject: [PATCH v5 06/15] elfcore: make prpsinfo always get a nul terminated task comm
Date: Thu, 21 Oct 2021 03:45:13 +0000	[thread overview]
Message-ID: <20211021034516.4400-7-laoar.shao@gmail.com> (raw)
In-Reply-To: <20211021034516.4400-1-laoar.shao@gmail.com>

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.

struct elf_prpsinfo is used to dump the task information in userspace
coredump or kernel vmcore. Use TASK_COMM_LEN_16 instead of hard-coded 16
to make it more grepable, and use strscpy_pad() instead of strncpy() to
make it always get a nul terminated task comm.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Petr Mladek <pmladek@suse.com>
---
 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..69fa1a728964 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_16];
 	char				pr_psargs[ELF_PRARGSZ];
 };
 
diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index 2aaa15779d50..ee7ac09734ba 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_16];	/* 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


  parent reply	other threads:[~2021-10-21  3:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-21  3:45 [PATCH v5 00/15] extend task comm from 16 to 24 for CONFIG_BASE_FULL Yafang Shao
2021-10-21  3:45 ` [PATCH v5 01/15] fs/exec: make __set_task_comm always set a nul ternimated string Yafang Shao
2021-10-21  3:45 ` [PATCH v5 02/15] fs/exec: make __get_task_comm always get a nul terminated string Yafang Shao
2021-10-21  3:45 ` [PATCH v5 03/15] sched.h: introduce TASK_COMM_LEN_16 Yafang Shao
2021-10-21 21:55   ` Andrii Nakryiko
2021-10-22  6:23     ` Yafang Shao
2021-10-21  3:45 ` [PATCH v5 04/15] cn_proc: make connector comm always nul ternimated Yafang Shao
2021-10-21  3:45 ` [PATCH v5 05/15] drivers/infiniband: make setup_ctxt always get a nul terminated task comm Yafang Shao
2021-10-21  3:45 ` Yafang Shao [this message]
2021-10-21  3:45 ` [PATCH v5 07/15] samples/bpf/kern: use TASK_COMM_LEN instead of hard-coded 16 Yafang Shao
2021-10-21  3:45 ` [PATCH v5 08/15] samples/bpf/user: use TASK_COMM_LEN_16 " Yafang Shao
2021-10-21  3:45 ` [PATCH v5 09/15] tools/include: introduce TASK_COMM_LEN_16 Yafang Shao
2021-10-22  3:52 ` [PATCH v5 00/15] extend task comm from 16 to 24 for CONFIG_BASE_FULL Andrew Morton
2021-10-22  4:00   ` Kees Cook
2021-10-22  6:20     ` Yafang Shao

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