[PATCH] src: buffer is not null terminated

[PATCH] src: buffer is not null terminated

[Harsha Sharma]

Use snprintf() over strncpy() functions as the buffer is not null
terminated in strncpy().

Signed-off-by: Harsha Sharma <harshasharmaiitr@gmail.com>
---
 src/datatype.c | 2 +-
 src/iface.c    | 4 ++--
 src/netlink.c  | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/datatype.c b/src/datatype.c
index 94b1224..9439ea3 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -858,7 +858,7 @@ static uint32_t str2int(char *tmp, const char *c, int k)
 	if (k == 0)
 		return 0;
 
-	strncpy(tmp, c-k, k+1);
+	snprintf(tmp, k+1, "%s", c-k);
 	return atoi(tmp);
 }
 
diff --git a/src/iface.c b/src/iface.c
index 9936388..d0e1834 100644
--- a/src/iface.c
+++ b/src/iface.c
@@ -53,7 +53,7 @@ static int data_cb(const struct nlmsghdr *nlh, void *data)
 	iface = xmalloc(sizeof(struct iface));
 	iface->ifindex = ifm->ifi_index;
 	mnl_attr_parse(nlh, sizeof(*ifm), data_attr_cb, tb);
-	strncpy(iface->name, mnl_attr_get_str(tb[IFLA_IFNAME]), IFNAMSIZ);
+	snprintf(iface->name, IFNAMSIZ, "%s", mnl_attr_get_str(tb[IFLA_IFNAME]));
 	list_add(&iface->list, &iface_list);
 
 	return MNL_CB_OK;
@@ -139,7 +139,7 @@ char *nft_if_indextoname(unsigned int ifindex, char *name)
 
 	list_for_each_entry(iface, &iface_list, list) {
 		if (iface->ifindex == ifindex) {
-			strncpy(name, iface->name, IFNAMSIZ);
+			snprintf(name, IFNAMSIZ, "%s", iface->name);
 			return name;
 		}
 	}
diff --git a/src/netlink.c b/src/netlink.c
index d5d410a..f69a5b9 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -386,7 +386,7 @@ static void netlink_gen_verdict(const struct expr *expr,
 	switch (expr->verdict) {
 	case NFT_JUMP:
 	case NFT_GOTO:
-		strncpy(data->chain, expr->chain, NFT_CHAIN_MAXNAMELEN);
+		snprintf(data->chain, NFT_CHAIN_MAXNAMELEN, "%s", expr->chain);
 		data->chain[NFT_CHAIN_MAXNAMELEN-1] = '\0';
 		break;
 	}
@@ -2915,7 +2915,7 @@ static int netlink_events_newgen_cb(const struct nlmsghdr *nlh, int type,
 		case NFTA_GEN_PROC_NAME:
 			if (mnl_attr_validate(attr, MNL_TYPE_NUL_STRING) < 0)
 				break;
-			strncpy(name, mnl_attr_get_str(attr), sizeof(name));
+			snprintf(name, sizeof(name), "%s", mnl_attr_get_str(attr));
 			break;
 		case NFTA_GEN_PROC_ID:
 			if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
-- 
2.11.0

Re: [Outreachy kernel] [PATCH] src: buffer is not null terminated

[Julia Lawall]

The subject line is not very clear.  Apparently, some buffer (which one?)
is not null terminated (but what will you do about it?).  It would be
better to say what is done inthe subject line, eg Use snprintf rather than
strncpy, and then as you already do explain why the change is desirable in
the commit log.  Then one is somehow better oriented to what is going on.

julia

On Mon, 9 Oct 2017, Harsha Sharma wrote:

> Use snprintf() over strncpy() functions as the buffer is not null
> terminated in strncpy().
>
> Signed-off-by: Harsha Sharma <harshasharmaiitr@gmail.com>
> ---
>  src/datatype.c | 2 +-
>  src/iface.c    | 4 ++--
>  src/netlink.c  | 4 ++--
>  3 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/src/datatype.c b/src/datatype.c
> index 94b1224..9439ea3 100644
> --- a/src/datatype.c
> +++ b/src/datatype.c
> @@ -858,7 +858,7 @@ static uint32_t str2int(char *tmp, const char *c, int k)
>  	if (k == 0)
>  		return 0;
>
> -	strncpy(tmp, c-k, k+1);
> +	snprintf(tmp, k+1, "%s", c-k);
>  	return atoi(tmp);
>  }
>
> diff --git a/src/iface.c b/src/iface.c
> index 9936388..d0e1834 100644
> --- a/src/iface.c
> +++ b/src/iface.c
> @@ -53,7 +53,7 @@ static int data_cb(const struct nlmsghdr *nlh, void *data)
>  	iface = xmalloc(sizeof(struct iface));
>  	iface->ifindex = ifm->ifi_index;
>  	mnl_attr_parse(nlh, sizeof(*ifm), data_attr_cb, tb);
> -	strncpy(iface->name, mnl_attr_get_str(tb[IFLA_IFNAME]), IFNAMSIZ);
> +	snprintf(iface->name, IFNAMSIZ, "%s", mnl_attr_get_str(tb[IFLA_IFNAME]));
>  	list_add(&iface->list, &iface_list);
>
>  	return MNL_CB_OK;
> @@ -139,7 +139,7 @@ char *nft_if_indextoname(unsigned int ifindex, char *name)
>
>  	list_for_each_entry(iface, &iface_list, list) {
>  		if (iface->ifindex == ifindex) {
> -			strncpy(name, iface->name, IFNAMSIZ);
> +			snprintf(name, IFNAMSIZ, "%s", iface->name);
>  			return name;
>  		}
>  	}
> diff --git a/src/netlink.c b/src/netlink.c
> index d5d410a..f69a5b9 100644
> --- a/src/netlink.c
> +++ b/src/netlink.c
> @@ -386,7 +386,7 @@ static void netlink_gen_verdict(const struct expr *expr,
>  	switch (expr->verdict) {
>  	case NFT_JUMP:
>  	case NFT_GOTO:
> -		strncpy(data->chain, expr->chain, NFT_CHAIN_MAXNAMELEN);
> +		snprintf(data->chain, NFT_CHAIN_MAXNAMELEN, "%s", expr->chain);
>  		data->chain[NFT_CHAIN_MAXNAMELEN-1] = '\0';
>  		break;
>  	}
> @@ -2915,7 +2915,7 @@ static int netlink_events_newgen_cb(const struct nlmsghdr *nlh, int type,
>  		case NFTA_GEN_PROC_NAME:
>  			if (mnl_attr_validate(attr, MNL_TYPE_NUL_STRING) < 0)
>  				break;
> -			strncpy(name, mnl_attr_get_str(attr), sizeof(name));
> +			snprintf(name, sizeof(name), "%s", mnl_attr_get_str(attr));
>  			break;
>  		case NFTA_GEN_PROC_ID:
>  			if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
> --
> 2.11.0
>
> --
> You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
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> For more options, visit https://groups.google.com/d/optout.
>

Re: [Outreachy kernel] [PATCH] src: buffer is not null terminated

[Harsha Sharma]

On Mon, Oct 9, 2017 at 12:36 AM, Julia Lawall <julia.lawall@lip6.fr> wrote:
> The subject line is not very clear.  Apparently, some buffer (which one?)
> is not null terminated (but what will you do about it?).  It would be
> better to say what is done inthe subject line, eg Use snprintf rather than
> strncpy, and then as you already do explain why the change is desirable in
> the commit log.  Then one is somehow better oriented to what is going on.
>

Hi,
Thanks for your feedback.
I have sent another version for the patch.
Thanks for your time :)

Regards,
Harsha Sharma

> julia
>
> On Mon, 9 Oct 2017, Harsha Sharma wrote:
>
>> Use snprintf() over strncpy() functions as the buffer is not null
>> terminated in strncpy().
>>
>> Signed-off-by: Harsha Sharma <harshasharmaiitr@gmail.com>
>> ---
>>  src/datatype.c | 2 +-
>>  src/iface.c    | 4 ++--
>>  src/netlink.c  | 4 ++--
>>  3 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/datatype.c b/src/datatype.c
>> index 94b1224..9439ea3 100644
>> --- a/src/datatype.c
>> +++ b/src/datatype.c
>> @@ -858,7 +858,7 @@ static uint32_t str2int(char *tmp, const char *c, int k)
>>       if (k == 0)
>>               return 0;
>>
>> -     strncpy(tmp, c-k, k+1);
>> +     snprintf(tmp, k+1, "%s", c-k);
>>       return atoi(tmp);
>>  }
>>
>> diff --git a/src/iface.c b/src/iface.c
>> index 9936388..d0e1834 100644
>> --- a/src/iface.c
>> +++ b/src/iface.c
>> @@ -53,7 +53,7 @@ static int data_cb(const struct nlmsghdr *nlh, void *data)
>>       iface = xmalloc(sizeof(struct iface));
>>       iface->ifindex = ifm->ifi_index;
>>       mnl_attr_parse(nlh, sizeof(*ifm), data_attr_cb, tb);
>> -     strncpy(iface->name, mnl_attr_get_str(tb[IFLA_IFNAME]), IFNAMSIZ);
>> +     snprintf(iface->name, IFNAMSIZ, "%s", mnl_attr_get_str(tb[IFLA_IFNAME]));
>>       list_add(&iface->list, &iface_list);
>>
>>       return MNL_CB_OK;
>> @@ -139,7 +139,7 @@ char *nft_if_indextoname(unsigned int ifindex, char *name)
>>
>>       list_for_each_entry(iface, &iface_list, list) {
>>               if (iface->ifindex == ifindex) {
>> -                     strncpy(name, iface->name, IFNAMSIZ);
>> +                     snprintf(name, IFNAMSIZ, "%s", iface->name);
>>                       return name;
>>               }
>>       }
>> diff --git a/src/netlink.c b/src/netlink.c
>> index d5d410a..f69a5b9 100644
>> --- a/src/netlink.c
>> +++ b/src/netlink.c
>> @@ -386,7 +386,7 @@ static void netlink_gen_verdict(const struct expr *expr,
>>       switch (expr->verdict) {
>>       case NFT_JUMP:
>>       case NFT_GOTO:
>> -             strncpy(data->chain, expr->chain, NFT_CHAIN_MAXNAMELEN);
>> +             snprintf(data->chain, NFT_CHAIN_MAXNAMELEN, "%s", expr->chain);
>>               data->chain[NFT_CHAIN_MAXNAMELEN-1] = '\0';
>>               break;
>>       }
>> @@ -2915,7 +2915,7 @@ static int netlink_events_newgen_cb(const struct nlmsghdr *nlh, int type,
>>               case NFTA_GEN_PROC_NAME:
>>                       if (mnl_attr_validate(attr, MNL_TYPE_NUL_STRING) < 0)
>>                               break;
>> -                     strncpy(name, mnl_attr_get_str(attr), sizeof(name));
>> +                     snprintf(name, sizeof(name), "%s", mnl_attr_get_str(attr));
>>                       break;
>>               case NFTA_GEN_PROC_ID:
>>                       if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
>> --
>> 2.11.0
>>
>> --
>> You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com.
>> To post to this group, send email to outreachy-kernel@googlegroups.com.
>> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20171008185825.21202-1-harshasharmaiitr%40gmail.com.
>> For more options, visit https://groups.google.com/d/optout.
>>