Messages in this thread |  | | Subject | Re: [PATCH -next] GRE: Use strlcat() for size checking | | From | Ben Hutchings <> | | Date | Wed, 27 Mar 2013 20:06:16 +0000 |
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On Wed, 2013-03-27 at 19:48 +0100, Geert Uytterhoeven wrote: > On m68k, gcc tries to be smart and turns > > strncat(name, "%d", 2); > > into a call to strlen() and a 16-bit store, causing a link failure, > as arch/m68k/include/asm/string.h provides strlen() using a macro: > > ERROR: "strlen" [net/ipv4/ip_tunnel.ko] undefined!
Perhaps you should fix the string library for m68k, then!
> Use strlcat() instead to avoid this, which also allows to simplify the > check for buffer overflows.
It looks like you're also fixing an off-by-one error: the maximum length of ops->kind will be IFNAMSIZ - 3 (just enough to add "%d" and the null terminator), rather than IFNAMSIZ - 4.
Ben.
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> > -- > Compile-tested only > > http://kisskb.ellerman.id.au/kisskb/buildresult/8462108/ > --- > net/ipv4/ip_tunnel.c | 5 ++--- > 1 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c > index 9d96b68..8dbe672 100644 > --- a/net/ipv4/ip_tunnel.c > +++ b/net/ipv4/ip_tunnel.c > @@ -284,12 +284,11 @@ static struct net_device *__ip_tunnel_create(struct net *net, > if (parms->name[0]) > strlcpy(name, parms->name, IFNAMSIZ); > else { > - if (strlen(ops->kind) + 3 >= IFNAMSIZ) { > + strlcpy(name, ops->kind, IFNAMSIZ); > + if (strlcat(name, "%d", IFNAMSIZ) >= IFNAMSIZ) { > err = -E2BIG; > goto failed; > } > - strlcpy(name, ops->kind, IFNAMSIZ); > - strncat(name, "%d", 2); > } > > ASSERT_RTNL();
-- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
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