linux-kernel - Re: [PATCH v4 4/9] vsprintf: Consolidate handling of unknown pointer specifiers

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Date:   Fri, 06 Apr 2018 18:00:59 -0700
From:   Joe Perches <joe@...ches.com>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Petr Mladek <pmladek@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Tobin C . Harding" <me@...in.cc>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 4/9] vsprintf: Consolidate handling of unknown
 pointer specifiers

On Sat, 2018-04-07 at 09:33 +0900, Sergey Senozhatsky wrote:
> Hi Joe,
> 
> On (04/06/18 16:59), Joe Perches wrote:
> > > 
> > > Can we tweak checkpatch to catch such things?
> > 
> > Not really, no.
> > 
> > Adding regex logic for this is tricky at best
> > and probably not worth the effort because of
> > the various bits of patch contexts aren't
> > necessarily visible.
> 
> Agreed. I was more thinking about catching "... %p" and saying
> that we'd rather prefer either "... %p," or "... %p " or "... %p\n".
> Doesn't sound so complex, can probably catch something fishy one day
> (or may be not), and more or less is visible to checkpatch. Well,
> more or less...

This finds the current two bad uses in addition to
the existing similar message for string concatenation
without a space char between concatenated fragments.

For example:

WARNING: break quoted strings at a space character
#3550: FILE: drivers/scsi/megaraid/megaraid_sas_base.c:3550:
+			dev_notice(&instance->pdev->dev, "moving cmd[%d]:%p:%d:%p"
+					"on the defer queue as internal\n",

WARNING: vsprintf %p<extension> string concatenation
#3550: FILE: drivers/scsi/megaraid/megaraid_sas_base.c:3550:
+			dev_notice(&instance->pdev->dev, "moving cmd[%d]:%p:%d:%p"
+					"on the defer queue as internal\n",

I think the new message is not that useful really as the
existing warning is probably enough.

---
 scripts/checkpatch.pl | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index eb534d48140e..a0e43232431e 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5313,6 +5313,12 @@ sub process {
 			     "break quoted strings at a space character\n" . $hereprev);
 		}
 
+# check for vsprintf pointer extension concatenation
+		if ($prevrawline =~ /\%p"\s*$/ && $rawline =~ /^\+\s*"\w/) {
+			WARN('POINTER_CONCATENATION',
+			     "vsprintf %p<extension> string concatenation\n" . $hereprev);
+		}
+
 # check for an embedded function name in a string when the function is known
 # This does not work very well for -f --file checking as it depends on patch
 # context providing the function name or a single line form for in-file