Re: [PATCH] objtool: check: give big enough buffer for pv_ops

From: Josh Poimboeuf
Date: Thu Jan 20 2022 - 18:09:46 EST


On Thu, Jan 20, 2022 at 02:58:13PM -0800, Josh Poimboeuf wrote:
> On Fri, Jan 14, 2022 at 09:53:07AM +0100, Peter Zijlstra wrote:
> > On Fri, Jan 14, 2022 at 07:57:56AM +0000, Sergei Trofimovich wrote:
> > > On gcc-12 build fails flagging possible buffer overflow:
> > >
> > > check.c: In function 'validate_call':
> > > check.c:2865:58: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 9 [-Werror=format-truncation=]
> > > 2865 | snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
> > > | ^~
> > >
> > > I think it's a valid warning:
> > >
> > > static char pvname[16];
> > > int idx;
> > > ...
> > > idx = (rel->addend / sizeof(void *));
> > > snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
> > >
> > > we have only 7 chars for %d while it could take up to 9.
> >
> > Right, very unlikely to have that many pv_ops, but it doesn't hurt to
> > fix this.
> >
> > Thanks!
>
> Alternatively, 'idx' could just be unsigned char, since pv_ops only has
> about ~80 entries max, but either way works for me. I'll queue it up.

Sergei, can you send a v2 with a valid Signed-off-by tag?

--
Josh