netdev - [PATCH v2 1/7] fs/exec: replace strlcpy with strscpy_pad in __set_task

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Message-Id: <20211120112738.45980-2-laoar.shao@gmail.com>
Date:   Sat, 20 Nov 2021 11:27:32 +0000
From:   Yafang Shao <laoar.shao@...il.com>
To:     akpm@...ux-foundation.org
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-perf-users@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        oliver.sang@...el.com, lkp@...el.com,
        Yafang Shao <laoar.shao@...il.com>,
        Kees Cook <keescook@...omium.org>,
        David Hildenbrand <david@...hat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Michal Miroslaw <mirq-linux@...e.qmqm.pl>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Matthew Wilcox <willy@...radead.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Petr Mladek <pmladek@...e.com>
Subject: [PATCH v2 1/7] fs/exec: replace strlcpy with strscpy_pad in __set_task_comm

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

Signed-off-by: Yafang Shao <laoar.shao@...il.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
Reviewed-by: David Hildenbrand <david@...hat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Michal Miroslaw <mirq-linux@...e.qmqm.pl>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: David Hildenbrand <david@...hat.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Kees Cook <keescook@...omium.org>
Cc: Petr Mladek <pmladek@...e.com>
---
 fs/exec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 537d92c41105..51d3cb4e3cdf 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1222,7 +1222,7 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
 {
 	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);
 }
-- 
2.17.1