[PATCH v2] checkpatch: add warning on invalid %p extensions

From: william . c . roberts
Date: Fri Feb 10 2017 - 17:43:37 EST


From: William Roberts <william.c.roberts@xxxxxxxxx>

The kernel supports %p extensions as documented in
Documentation/printk-formats.txt. Warn on possibly
improper use of non-extension characters.

One issue would be the usage of %pk when %pK should have
been used. This has a side-effect of appearing to work
alright, but does not respect the kptr_restrict setting
as %pK does.

Sample output:
WARNING: Invalid vsprintf pointer extension '%pk'
+ printk(KERN_INFO "Could not allocate IRQ %d for PCI Applicom device. %pk\n", dev->irq, pci_get_class); // NOT OK

WARNING: Invalid vsprintf pointer extension '%pn'
+ sprintf(buf, "%pn", x); // NOT OK

Signed-off-by: William Roberts <william.c.roberts@xxxxxxxxx>
---
scripts/checkpatch.pl | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 982c52c..fa22751 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6096,6 +6096,12 @@ sub process {
"recursive locking is bad, do not use this ever.\n" . $herecurr);
}

+# check for vsprintf extension %p<foo> misuses
+ if (get_quoted_string($line, $rawline) =~ /(\%[\*\d\.]*p(?![\WFfSsBKRraEhMmIiUDdgVCbGN]).)/) {
+ WARN("VSPRINTF_POINTER_EXTENSION",
+ "Invalid vsprintf pointer extension '$1'\n" . $herecurr);
+ }
+
# check for lockdep_set_novalidate_class
if ($line =~ /^.\s*lockdep_set_novalidate_class\s*\(/ ||
$line =~ /__lockdep_no_validate__\s*\)/ ) {
--
2.7.4