diff mbox series

[v8,4/8] bpftool: Ensure task comm is always NUL-terminated

Message ID 20240828030321.20688-5-laoar.shao@gmail.com (mailing list archive)
State Handled Elsewhere
Delegated to: BPF
Headers show
Series Improve the copy of task comm | expand

Checks

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bpf/vmtest-bpf-next-PR success PR summary
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netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 7 this patch: 7
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netdev/cc_maintainers warning 11 maintainers not CCed: andrii@kernel.org sdf@fomichev.me eddyz87@gmail.com haoluo@google.com jolsa@kernel.org daniel@iogearbox.net song@kernel.org yonghong.song@linux.dev kpsingh@kernel.org martin.lau@linux.dev john.fastabend@gmail.com
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Commit Message

Yafang Shao Aug. 28, 2024, 3:03 a.m. UTC 
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 <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
---
 tools/bpf/bpftool/pids.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Justin Stitt Sept. 12, 2024, 9:14 p.m. UTC | #1 
Hi,

On Wed, Aug 28, 2024 at 11:03:17AM GMT, Yafang Shao wrote:
> 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 <laoar.shao@gmail.com>
> 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';

...

>  		refs->ref_cnt++;
>  
>  		return;
> @@ -77,6 +78,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
>  	ref = &refs->refs[0];
>  	ref->pid = e->pid;
>  	memcpy(ref->comm, e->comm, sizeof(ref->comm));
> +	ref->comm[sizeof(ref->comm) - 1] = '\0';

Excuse my ignorance, do we not have a strscpy() equivalent usable in bpf
code?

>  	refs->ref_cnt = 1;
>  	refs->has_bpf_cookie = e->has_bpf_cookie;
>  	refs->bpf_cookie = e->bpf_cookie;
> -- 
> 2.43.5
> 

Thanks
Justin
Yafang Shao Sept. 13, 2024, 2:20 a.m. UTC | #2 
On Fri, Sep 13, 2024 at 5:14 AM Justin Stitt <justinstitt@google.com> wrote:
>
> Hi,
>
> On Wed, Aug 28, 2024 at 11:03:17AM GMT, Yafang Shao wrote:
> > 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 <laoar.shao@gmail.com>
> > 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';
>
> ...
>
> >               refs->ref_cnt++;
> >
> >               return;
> > @@ -77,6 +78,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
> >       ref = &refs->refs[0];
> >       ref->pid = e->pid;
> >       memcpy(ref->comm, e->comm, sizeof(ref->comm));
> > +     ref->comm[sizeof(ref->comm) - 1] = '\0';
>
> Excuse my ignorance, do we not have a strscpy() equivalent usable in bpf
> code?

To my knowledge, there is no direct equivalent of the standard
strcpy() function available in bpftool or libbpf code.
diff mbox series

Patch

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';
 		refs->ref_cnt++;
 
 		return;
@@ -77,6 +78,7 @@  static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
 	ref = &refs->refs[0];
 	ref->pid = e->pid;
 	memcpy(ref->comm, e->comm, sizeof(ref->comm));
+	ref->comm[sizeof(ref->comm) - 1] = '\0';
 	refs->ref_cnt = 1;
 	refs->has_bpf_cookie = e->has_bpf_cookie;
 	refs->bpf_cookie = e->bpf_cookie;