From: Jiri Benc <jbenc@redhat.com>
To: kernel-janitors@vger.kernel.org
Subject: Re: [bug report] vxlan: keep flags and vni in network byte order
Date: Fri, 11 Nov 2016 13:05:09 +0000 [thread overview]
Message-ID: <20161111140509.288e2fd4@griffin> (raw)
In-Reply-To: <20161111124941.GA3991@mwanda>
On Fri, 11 Nov 2016 15:49:41 +0300, Dan Carpenter wrote:
> Hello Jiri Benc,
>
> The patch 54bfd872bf16: "vxlan: keep flags and vni in network byte
> order" from Feb 16, 2016, leads to the following static checker
> warning:
>
> ./include/net/vxlan.h:340 vxlan_vni()
> warn: potential shift truncation. '0xffffff00 << 8'
>
> include/net/vxlan.h
> 335 static inline __be32 vxlan_vni(__be32 vni_field)
> 336 {
> 337 #if defined(__BIG_ENDIAN)
> 338 return (__force __be32)((__force u32)vni_field >> 8);
> 339 #else
> 340 return (__force __be32)((__force u32)(vni_field & VXLAN_VNI_MASK) << 8);
>
> Are you sure this is correct? VXLAN_VNI_MASK already has an << 8 shift
> so this feels like maybe it is a double shift.
The static checker clearly can't understand endian conversion macros.
VXLAN_VNI_MASK is:
cpu_to_be32(VXLAN_VID_MASK << 8)
Thus on little endian, it becomes 0x00ffffff.
Jiri
next prev parent reply other threads:[~2016-11-11 13:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-11 12:49 [bug report] vxlan: keep flags and vni in network byte order Dan Carpenter
2016-11-11 13:05 ` Jiri Benc [this message]
2016-11-11 13:12 ` Jiri Benc
2016-11-11 13:27 ` Dan Carpenter
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