* [PATCH net-next] net-ipv6: Fix alleged compiler warning in ipv6_exthdrs_len()
@ 2013-12-15 17:19 H.K. Jerry Chu
2013-12-16 1:31 ` David Miller
0 siblings, 1 reply; 5+ messages in thread
From: H.K. Jerry Chu @ 2013-12-15 17:19 UTC (permalink / raw)
To: hannes; +Cc: davem, netdev, Jerry Chu
From: Jerry Chu <hkchu@google.com>
It was reported that Commit 299603e8370a93dd5d8e8d800f0dff1ce2c53d36
("net-gro: Prepare GRO stack for the upcoming tunneling support")
triggered a compiler warning in ipv6_exthdrs_len():
net/ipv6/ip6_offload.c: In function ‘ipv6_gro_complete’:
net/ipv6/ip6_offload.c:178:24: warning: ‘optlen’ may be used uninitialized in this function [-Wmaybe-u
opth = (void *)opth + optlen;
^
net/ipv6/ip6_offload.c:164:22: note: ‘optlen’ was declared here
int len = 0, proto, optlen;
^
Note that there was no real bug here - optlen was never uninitialized
before use. (Was the version of gcc I used smarter to not complain?)
Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
---
net/ipv6/ip6_offload.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 7540a0e..6fb4162 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -160,8 +160,8 @@ out:
static int ipv6_exthdrs_len(struct ipv6hdr *iph,
const struct net_offload **opps)
{
- struct ipv6_opt_hdr *opth = NULL;
- int len = 0, proto, optlen;
+ struct ipv6_opt_hdr *opth = (void *)iph;
+ int len = 0, proto, optlen = sizeof(*iph);
proto = iph->nexthdr;
for (;;) {
@@ -172,10 +172,7 @@ static int ipv6_exthdrs_len(struct ipv6hdr *iph,
if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
break;
}
- if (opth == NULL)
- opth = (void *)(iph+1);
- else
- opth = (void *)opth + optlen;
+ opth = (void *)opth + optlen;
optlen = ipv6_optlen(opth);
len += optlen;
proto = opth->nexthdr;
--
1.8.5.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net-ipv6: Fix alleged compiler warning in ipv6_exthdrs_len()
2013-12-15 17:19 [PATCH net-next] net-ipv6: Fix alleged compiler warning in ipv6_exthdrs_len() H.K. Jerry Chu
@ 2013-12-16 1:31 ` David Miller
2013-12-16 2:30 ` Jerry Chu
0 siblings, 1 reply; 5+ messages in thread
From: David Miller @ 2013-12-16 1:31 UTC (permalink / raw)
To: hkchu; +Cc: hannes, netdev
From: "H.K. Jerry Chu" <hkchu@google.com>
Date: Sun, 15 Dec 2013 09:19:07 -0800
> From: Jerry Chu <hkchu@google.com>
>
> It was reported that Commit 299603e8370a93dd5d8e8d800f0dff1ce2c53d36
> ("net-gro: Prepare GRO stack for the upcoming tunneling support")
> triggered a compiler warning in ipv6_exthdrs_len():
>
> net/ipv6/ip6_offload.c: In function ‘ipv6_gro_complete’:
> net/ipv6/ip6_offload.c:178:24: warning: ‘optlen’ may be used uninitialized in this function [-Wmaybe-u
> opth = (void *)opth + optlen;
> ^
> net/ipv6/ip6_offload.c:164:22: note: ‘optlen’ was declared here
> int len = 0, proto, optlen;
> ^
> Note that there was no real bug here - optlen was never uninitialized
> before use. (Was the version of gcc I used smarter to not complain?)
>
> Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
What is this patch against?
It gets rejects when I try to apply it both with Hannes's patch reverted
and without it reverted.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net-ipv6: Fix alleged compiler warning in ipv6_exthdrs_len()
2013-12-16 1:31 ` David Miller
@ 2013-12-16 2:30 ` Jerry Chu
0 siblings, 0 replies; 5+ messages in thread
From: Jerry Chu @ 2013-12-16 2:30 UTC (permalink / raw)
To: David Miller; +Cc: hannes, netdev@vger.kernel.org
On Mon, Dec 16, 2013 at 9:31 AM, David Miller <davem@davemloft.net> wrote:
> From: "H.K. Jerry Chu" <hkchu@google.com>
> Date: Sun, 15 Dec 2013 09:19:07 -0800
>
>> From: Jerry Chu <hkchu@google.com>
>>
>> It was reported that Commit 299603e8370a93dd5d8e8d800f0dff1ce2c53d36
>> ("net-gro: Prepare GRO stack for the upcoming tunneling support")
>> triggered a compiler warning in ipv6_exthdrs_len():
>>
>> net/ipv6/ip6_offload.c: In function ‘ipv6_gro_complete’:
>> net/ipv6/ip6_offload.c:178:24: warning: ‘optlen’ may be used uninitialized in this function [-Wmaybe-u
>> opth = (void *)opth + optlen;
>> ^
>> net/ipv6/ip6_offload.c:164:22: note: ‘optlen’ was declared here
>> int len = 0, proto, optlen;
>> ^
>> Note that there was no real bug here - optlen was never uninitialized
>> before use. (Was the version of gcc I used smarter to not complain?)
>>
>> Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
>> Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
>
> What is this patch against?
>
> It gets rejects when I try to apply it both with Hannes's patch reverted
> and without it reverted.
It was against net-next of a few days old (and w/o Hannes's patch):
commit 68536053600425c24aba031c45f053d447eedd9c (netnext/master)
Author: Florent Fourcot <florent.fourcot@enst-bretagne.fr>
Date: Thu Dec 12 17:07:58 2013 +0100
ipv6: fix incorrect type in declaration
I just did a git pull and will submit one against the latest net-next.
(I did not see any conflict though. Not sure why you can't apply the patch.)
Jerry
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH net-next] net-ipv6: Fix alleged compiler warning in ipv6_exthdrs_len()
@ 2013-12-16 2:48 H.K. Jerry Chu
2013-12-16 5:27 ` David Miller
0 siblings, 1 reply; 5+ messages in thread
From: H.K. Jerry Chu @ 2013-12-16 2:48 UTC (permalink / raw)
To: hannes; +Cc: davem, netdev, Jerry Chu
From: Jerry Chu <hkchu@google.com>
It was reported that Commit 299603e8370a93dd5d8e8d800f0dff1ce2c53d36
("net-gro: Prepare GRO stack for the upcoming tunneling support")
triggered a compiler warning in ipv6_exthdrs_len():
net/ipv6/ip6_offload.c: In function ‘ipv6_gro_complete’:
net/ipv6/ip6_offload.c:178:24: warning: ‘optlen’ may be used uninitialized in this function [-Wmaybe-u
opth = (void *)opth + optlen;
^
net/ipv6/ip6_offload.c:164:22: note: ‘optlen’ was declared here
int len = 0, proto, optlen;
^
Note that there was no real bug here - optlen was never uninitialized
before use. (Was the version of gcc I used smarter to not complain?)
Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
---
net/ipv6/ip6_offload.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 08861f1..6fb4162 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -160,8 +160,8 @@ out:
static int ipv6_exthdrs_len(struct ipv6hdr *iph,
const struct net_offload **opps)
{
- struct ipv6_opt_hdr *opth = NULL;
- int len = 0, optlen = 0, proto;
+ struct ipv6_opt_hdr *opth = (void *)iph;
+ int len = 0, proto, optlen = sizeof(*iph);
proto = iph->nexthdr;
for (;;) {
@@ -172,12 +172,8 @@ static int ipv6_exthdrs_len(struct ipv6hdr *iph,
if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
break;
}
- if (opth == NULL) {
- opth = (void *)(iph+1);
- } else {
- optlen = ipv6_optlen(opth);
- opth = (void *)opth + optlen;
- }
+ opth = (void *)opth + optlen;
+ optlen = ipv6_optlen(opth);
len += optlen;
proto = opth->nexthdr;
}
--
1.8.5.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net-ipv6: Fix alleged compiler warning in ipv6_exthdrs_len()
2013-12-16 2:48 H.K. Jerry Chu
@ 2013-12-16 5:27 ` David Miller
0 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2013-12-16 5:27 UTC (permalink / raw)
To: hkchu; +Cc: hannes, netdev
From: "H.K. Jerry Chu" <hkchu@google.com>
Date: Sun, 15 Dec 2013 18:48:07 -0800
> From: Jerry Chu <hkchu@google.com>
>
> It was reported that Commit 299603e8370a93dd5d8e8d800f0dff1ce2c53d36
> ("net-gro: Prepare GRO stack for the upcoming tunneling support")
> triggered a compiler warning in ipv6_exthdrs_len():
>
> net/ipv6/ip6_offload.c: In function ‘ipv6_gro_complete’:
> net/ipv6/ip6_offload.c:178:24: warning: ‘optlen’ may be used uninitialized in this function [-Wmaybe-u
> opth = (void *)opth + optlen;
> ^
> net/ipv6/ip6_offload.c:164:22: note: ‘optlen’ was declared here
> int len = 0, proto, optlen;
> ^
> Note that there was no real bug here - optlen was never uninitialized
> before use. (Was the version of gcc I used smarter to not complain?)
>
> Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Applied, thank you.
^ permalink raw reply [flat|nested] 5+ messages in thread
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