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Date: Fri, 10 Feb 2017 23:31:35 +0000
From: "Roberts, William C" <william.c.roberts@...el.com>
To: Joe Perches <joe@...ches.com>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "apw@...onical.com" <apw@...onical.com>,
Andew Morton <akpm@...ux-foundation.org>
CC: "keescook@...omium.org" <keescook@...omium.org>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: RE: [PATCH] checkpatch: add warning on %pk instead of %pK usage
> -----Original Message-----
> From: Joe Perches [mailto:joe@...ches.com]
> Sent: Friday, February 10, 2017 2:50 PM
> To: Roberts, William C <william.c.roberts@...el.com>; linux-
> kernel@...r.kernel.org; apw@...onical.com; Andew Morton <akpm@...ux-
> foundation.org>
> Cc: keescook@...omium.org; kernel-hardening@...ts.openwall.com
> Subject: Re: [PATCH] checkpatch: add warning on %pk instead of %pK usage
>
> On Fri, 2017-02-10 at 22:26 +0000, Roberts, William C wrote:
> > <snip>
> >
> > > >
> > > > On Fri, 2017-02-10 at 11:37 -0800, william.c.roberts@...el.com wrote:
> > > > > From: William Roberts <william.c.roberts@...el.com>
> > > > >
> > > > > Sample output:
> > > > > WARNING: %pk is close to %pK, did you mean %pK?.
> > > > > \#20: FILE: drivers/char/applicom.c:230:
> > > > > + printk(KERN_INFO "Could not allocate IRQ %d for
> PCI
> > > >
> > > > Applicom
> > > > > +device. %pk\n", dev->irq, pci_get_class);
> > > >
> > > > There isn't a single instance of this in the kernel tree.
> > > >
> > > > Maybe if this is really useful, then all the %p<foo> extensions
> > > > should be enumerated and all unknown uses should have warnings.
> > >
> > > I was thinking of doing that, but I figured I would start with the
> > > bare minimum patch.
> > >
> > > >
> > > > Something like:
> > > >
> > > > ---
> > > > scripts/checkpatch.pl | 9 +++++++++
> > > > 1 file changed, 9 insertions(+)
> > > >
> > > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index
> > > > ad5ea5c545b2..8a90b457e8b5 100755
> > > > --- a/scripts/checkpatch.pl
> > > > +++ b/scripts/checkpatch.pl
> > > > @@ -5305,6 +5305,15 @@ sub process {
> > > > }
> > > > }
> > > >
> > > > +# check for vsprintf extension %p<foo> misuses
> > > > + if ($line =~ /\b$logFunctions\s*\(.*$String/) {
> >
> > I don't see the normal string formatting routines in that list... I think this is too
> restrictive.
>
> I don't. There are no "normal" string formatting routines.
By "normal" I'm referring to things that call into pointer(), just casually looking
I see bstr_printf vsnprintf kvasprintf, which would be easy enough to add
> What do you think is missing? sn?printf ? That's easy to add.
The problem starts to get hairy when we think of how often folks roll their own logging macros (see some small sampling at the end).
I think we would want to add DEBUG DBG and sn?printf and maybe consider dropping the \b on the regex so it's a bit more matchy but still shouldn't
end up matching on any ASM as you pointed out in the V2 nack.
Ill break this down into:
1. the patch as I know you'll take it, as you wrote it :-P
2. Adding to the logging macros
3. exploring making it less matchy
Data:
arch/alpha/kernel/pci_iommu.c:25:# define DBGA(args...) printk(KERN_DEBUG args)
arch/alpha/kernel/pci_iommu.c:30:# define DBGA2(args...) printk(KERN_DEBUG args)
arch/alpha/kernel/core_tsunami.c:50:# define DBG_CFG(args) printk args
arch/alpha/kernel/core_titan.c:50:# define DBG_CFG(args) printk args
arch/alpha/kernel/ptrace.c:34:#define DBG(fac,args) {if ((fac) & DEBUG) printk args;}
arch/alpha/kernel/core_apecs.c:42:# define DBGC(args) printk args
arch/alpha/kernel/core_irongate.c:38:# define DBG_CFG(args) printk args
arch/alpha/kernel/core_wildfire.c:30:# define DBG_CFG(args) printk args
arch/alpha/kernel/smc37c93x.c:18:# define DBG_DEVS(args) printk args
arch/alpha/boot/misc.c:27:#define puts srm_printk
arch/alpha/mm/numa.c:27:#define DBGDCONT(args...) printk(args)
arch/powerpc/sysdev/tsi108_pci.c:43:#define DBG(x...) printk(x)
arch/powerpc/sysdev/ge/ge_pic.c:31:#define DBG(fmt...) do { printk(KERN_DEBUG "gef_pic: " fmt); } while (0)
arch/powerpc/sysdev/tsi108_dev.c:34:#define DBG(fmt...) do { printk(fmt); } while(0)
arch/powerpc/sysdev/mpic.c:45:#define DBG(fmt...) printk(fmt)
arch/powerpc/kernel/process.c:69:#define TM_DEBUG(x...) printk(KERN_INFO x)
arch/powerpc/kernel/vdso.c:42:#define DBG(fmt...) printk(fmt)
arch/powerpc/kernel/legacy_serial.c:21:#define DBG(fmt...) do { printk(fmt); } while(0)
arch/powerpc/kernel/traps.c:89:#define TM_DEBUG(x...) printk(KERN_INFO x)
arch/powerpc/kernel/prom.c:65:#define DBG(fmt...) printk(KERN_ERR fmt)
arch/powerpc/kvm/book3s_paired_singles.c:33:#define dprintk printk
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