Re: [PATCH v7 4/8] bpftool: Ensure task comm is always NUL-terminated

Hi Yafang,

On Sun, Aug 18, 2024 at 10:27:01AM GMT, Yafang Shao wrote:

On Sat, Aug 17, 2024 at 4:39 PM Alejandro Colomar [off-list ref] wrote:

quoted

Hi Yafang,

On Sat, Aug 17, 2024 at 10:56:20AM GMT, Yafang Shao wrote:

quoted

Let's explicitly ensure the destination string is NUL-terminated. This way,
it won't be affected by changes to the source string.

Signed-off-by: Yafang Shao <redacted>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
---
 tools/bpf/bpftool/pids.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/bpf/bpftool/pids.c b/tools/bpf/bpftool/pids.c
index 9b898571b49e..23f488cf1740 100644
--- a/tools/bpf/bpftool/pids.c
+++ b/tools/bpf/bpftool/pids.c

@@ -54,6 +54,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
              ref = &refs->refs[refs->ref_cnt];
              ref->pid = e->pid;
              memcpy(ref->comm, e->comm, sizeof(ref->comm));
+             ref->comm[sizeof(ref->comm) - 1] = '\0';

Why doesn't this use strscpy()?

bpftool is a userspace tool, so strscpy() is only applicable in kernel
code, correct?

Ahh, makes sense.  LGTM, then.  Maybe the closest user-space function to
strscpy(9) would be strlcpy(3), but I don't know how old of a glibc you
support.  strlcpy(3) is currently in POSIX, and supported by both glibc
and musl, but that's too recent.

Have a lovely day!
Alex

--
Regards
Yafang

-- 
<https://www.alejandro-colomar.es/>