[PATCH] dns: remove redundant zero length namelen check

[PATCH] dns: remove redundant zero length namelen check

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The zero namelen check is redundant as it has already been checked
for zero at the start of the function.  Remove the redundant check.

Addresses-Coverity: ("Logically Dead Code")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 net/dns_resolver/dns_query.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
index 76338c38738a..19aa32fc1802 100644
--- a/net/dns_resolver/dns_query.c
+++ b/net/dns_resolver/dns_query.c
@@ -94,8 +94,6 @@ int dns_query(const char *type, const char *name, size_t namelen,
 		desclen += typelen + 1;
 	}
 
-	if (!namelen)
-		namelen = strnlen(name, 256);
 	if (namelen < 3 || namelen > 255)
 		return -EINVAL;
 	desclen += namelen + 1;
-- 
2.20.1

[PATCH] dns: remove redundant zero length namelen check

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The zero namelen check is redundant as it has already been checked
for zero at the start of the function.  Remove the redundant check.

Addresses-Coverity: ("Logically Dead Code")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 net/dns_resolver/dns_query.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
index 76338c38738a..19aa32fc1802 100644
--- a/net/dns_resolver/dns_query.c
+++ b/net/dns_resolver/dns_query.c
@@ -94,8 +94,6 @@ int dns_query(const char *type, const char *name, size_t namelen,
 		desclen += typelen + 1;
 	}
 
-	if (!namelen)
-		namelen = strnlen(name, 256);
 	if (namelen < 3 || namelen > 255)
 		return -EINVAL;
 	desclen += namelen + 1;
-- 
2.20.1

Re: [PATCH] dns: remove redundant zero length namelen check

[David Miller]

From: Colin King <colin.king@canonical.com>
Date: Tue,  9 Apr 2019 13:59:12 +0100

> From: Colin Ian King <colin.king@canonical.com>
> 
> The zero namelen check is redundant as it has already been checked
> for zero at the start of the function.  Remove the redundant check.
> 
> Addresses-Coverity: ("Logically Dead Code")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Applied to net-next.

However it does look like two sets of semantics were considered.
In one case rejecting a zero namelen and in another having it
mean whatever the strings length is modulo the max of 256.

Re: [PATCH] dns: remove redundant zero length namelen check

[David Miller]

From: Colin King <colin.king@canonical.com>
Date: Tue,  9 Apr 2019 13:59:12 +0100

> From: Colin Ian King <colin.king@canonical.com>
> 
> The zero namelen check is redundant as it has already been checked
> for zero at the start of the function.  Remove the redundant check.
> 
> Addresses-Coverity: ("Logically Dead Code")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Applied to net-next.

However it does look like two sets of semantics were considered.
In one case rejecting a zero namelen and in another having it
mean whatever the strings length is modulo the max of 256.

Re: [PATCH] dns: remove redundant zero length namelen check

[David Howells]

David Miller <davem@davemloft.net> wrote:

> > The zero namelen check is redundant as it has already been checked
> > for zero at the start of the function.  Remove the redundant check.
> > 
> > Addresses-Coverity: ("Logically Dead Code")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> 
> Applied to net-next.
> 
> However it does look like two sets of semantics were considered.
> In one case rejecting a zero namelen and in another having it
> mean whatever the strings length is modulo the max of 256.

It probably makes sense to merge the:

	if (namelen < 3 || namelen > 255)
		return -EINVAL;

check into the earlier:

	if (!name || namelen == 0)
		return -EINVAL;

check too.

David

Re: [PATCH] dns: remove redundant zero length namelen check

[David Howells]

David Miller <davem@davemloft.net> wrote:

> > The zero namelen check is redundant as it has already been checked
> > for zero at the start of the function.  Remove the redundant check.
> > 
> > Addresses-Coverity: ("Logically Dead Code")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> 
> Applied to net-next.
> 
> However it does look like two sets of semantics were considered.
> In one case rejecting a zero namelen and in another having it
> mean whatever the strings length is modulo the max of 256.

It probably makes sense to merge the:

	if (namelen < 3 || namelen > 255)
		return -EINVAL;

check into the earlier:

	if (!name || namelen = 0)
		return -EINVAL;

check too.

David