Prefer `strscpy` over `strncpy`.
Signed-off-by: Justin Stitt <[email protected]>
---
Note:
It is hard to tell if there was a bug here in the first place but it's better
to use a more robust and less ambiguous interface anyways.
`helper->name` has a size of 16 and the 3rd argument to `strncpy`
(NF_CT_HELPER_LEN) is also 16. This means that depending on where
`dest`'s offset is relative to `regs->data` which has a length of 20,
there may be a chance the dest buffer ends up non NUL-terminated. This
is probably fine though as the destination buffer in this case may be
fine being non NUL-terminated. If this is the case, we should probably
opt for `strtomem` instead of `strscpy`.
---
net/netfilter/nft_ct.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 38958e067aa8..10126559038b 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -108,7 +108,7 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
helper = rcu_dereference(help->helper);
if (helper == NULL)
goto err;
- strncpy((char *)dest, helper->name, NF_CT_HELPER_NAME_LEN);
+ strscpy((char *)dest, helper->name, NF_CT_HELPER_NAME_LEN);
return;
#ifdef CONFIG_NF_CONNTRACK_LABELS
case NFT_CT_LABELS: {
--
2.41.0.640.ga95def55d0-goog
Justin Stitt <[email protected]> wrote:
> Prefer `strscpy` over `strncpy`.
Just like all other nft_*.c changes, this relies on zeroing
the remaining buffer, so please use strscpy_pad if this is
really needed for some reason.
On Tue, Aug 8, 2023 at 4:40 PM Florian Westphal <[email protected]> wrote:
>
> Justin Stitt <[email protected]> wrote:
> > Prefer `strscpy` over `strncpy`.
>
> Just like all other nft_*.c changes, this relies on zeroing
> the remaining buffer, so please use strscpy_pad if this is
> really needed for some reason.
I'm soon sending a v2 series that prefers `strscpy_pad` to `strscpy`
as per Florian and Kees' feedback.
It should be noted that there was a similar refactor that took place
in this tree as well [1]. Wolfram Sang opted for `strscpy` as a
replacement to `strlcpy`. I assume the zero-padding is not needed in
such instances, right?
[1]: https://lore.kernel.org/all/[email protected]/
Thanks.