From: Yafang Shao <laoar.shao@xxxxxxxxx> 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/20211101060419.4682-1-laoar.shao@xxxxxxxxx/ [2]. https://lore.kernel.org/lkml/CALOAHbAx55AUo3bm8ZepZSZnw7A08cvKPdPyNTf=E_tPqmw5hw@xxxxxxxxxxxxxx/ 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/20211120112738.45980-1-laoar.shao@xxxxxxxxx Link: https://lkml.kernel.org/r/20211120112738.45980-2-laoar.shao@xxxxxxxxx Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx> Cc: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> Cc: Michal Miroslaw <mirq-linux@xxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Andrii Nakryiko <andrii@xxxxxxxxxx> Cc: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 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); } _
