Infinite loop in checkpatch.pl

Infinite loop in checkpatch.pl

[Alexander Potapenko]

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Hi folks,

I've noticed that checkpatch.pl chokes on the following file (also attached):

==================================
$ cat test-checkpatch.txt
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
@@ -504,6 +504,25 @@ static void
test_memcpy_aligned_to_unaligned2(struct kunit *test)
+ EXPECTATION_NO_REPORT(expect);                              \
+ volatile uint##size##_t uninit;                             \
==================================


, getting into an infinite loop in annotate_values().
The following patch helps it to proceed:

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 78cc595b98ce1..01d998b416a51 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2240,8 +2240,13 @@ sub annotate_values {
                        print "C($1)\n" if ($dbg_values > 1);
                }
                if (defined $1) {
-                       $cur = substr($cur, length($1));
-                       $res .= $type x length($1);
+                       if (length($1)) {
+                               $cur = substr($cur, length($1));
+                               $res .= $type x length($1);
+                       } else {
+                               $res .= $cur;
+                               $cur = "";
+                       }
                }
        }

, but I have no idea how to test it properly.

Could you please take a look?


Thanks,
Alex

-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Liana Sebastian
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg

[-- Attachment #2: test-checkpatch.txt --]
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diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
@@ -504,6 +504,25 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
+		EXPECTATION_NO_REPORT(expect);                              \
+		volatile uint##size##_t uninit;                             \

Re: Infinite loop in checkpatch.pl

[Joe Perches]

On Fri, 2023-03-03 at 15:28 +0100, Alexander Potapenko wrote:
> Hi folks,
> 
> I've noticed that checkpatch.pl chokes on the following file (also attached):
> 
> ==================================
> $ cat test-checkpatch.txt
> diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
> @@ -504,6 +504,25 @@ static void
> test_memcpy_aligned_to_unaligned2(struct kunit *test)
> + EXPECTATION_NO_REPORT(expect);                              \
> + volatile uint##size##_t uninit;                             \

checkpatch isn't a syntax complete c parser.  Don't expect to be.

Re: Infinite loop in checkpatch.pl

[Alexander Potapenko]

On Fri, Mar 3, 2023 at 5:53 PM Joe Perches <joe@perches.com> wrote:
>
> On Fri, 2023-03-03 at 15:28 +0100, Alexander Potapenko wrote:
> > Hi folks,
> >
> > I've noticed that checkpatch.pl chokes on the following file (also attached):
> >
> > ==================================
> > $ cat test-checkpatch.txt
> > diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
> > @@ -504,6 +504,25 @@ static void
> > test_memcpy_aligned_to_unaligned2(struct kunit *test)
> > + EXPECTATION_NO_REPORT(expect);                              \
> > + volatile uint##size##_t uninit;                             \
>
> checkpatch isn't a syntax complete c parser.  Don't expect to be.

That's understandable, and I sure don't. But as a user I expect it to
not loop infinitely, and I think that's also reasonable.
The example I gave is not a randomly generated code snippet, but an
excerpt from a valid patch that I sent earlier today:
https://lore.kernel.org/lkml/20230303141433.3422671-4-glider@google.com/,
which checkpatch cannot process.


-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Liana Sebastian
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg

Re: Infinite loop in checkpatch.pl

[Joe Perches]

On Fri, 2023-03-03 at 21:53 +0100, Alexander Potapenko wrote:
> On Fri, Mar 3, 2023 at 5:53 PM Joe Perches <joe@perches.com> wrote:
> > 
> > On Fri, 2023-03-03 at 15:28 +0100, Alexander Potapenko wrote:
> > > Hi folks,
> > > 
> > > I've noticed that checkpatch.pl chokes on the following file (also attached):
> > > 
> > > ==================================
> > > $ cat test-checkpatch.txt
> > > diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
> > > @@ -504,6 +504,25 @@ static void
> > > test_memcpy_aligned_to_unaligned2(struct kunit *test)
> > > + EXPECTATION_NO_REPORT(expect);                              \
> > > + volatile uint##size##_t uninit;                             \
> > 
> > checkpatch isn't a syntax complete c parser.  Don't expect to be.
> 
> That's understandable, and I sure don't. But as a user I expect it to
> not loop infinitely, and I think that's also reasonable.
> The example I gave is not a randomly generated code snippet, but an
> excerpt from a valid patch that I sent earlier today:
> https://lore.kernel.org/lkml/20230303141433.3422671-4-glider@google.com/,
> which checkpatch cannot process.

I think this may be appropriate instead.  Andy W?
---
 scripts/checkpatch.pl | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index bd44d12965c98..3328fb9f6d048 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -999,7 +999,9 @@ if (defined($typedefsfile)) {
 }
 
 sub build_types {
-	my $mods = "(?x:  \n" . join("|\n  ", (@modifierList, @modifierListFile)) . "\n)";
+	my $mods = "(?x:  \n" . join("|\n  ", @modifierList);
+	$mods .= "|(?^:  \n" . join("|\n  ", @modifierListFile) . "\n)" if ($#modifierListFile >= 0);
+	$mods .= ')';
 	my $all = "(?x:  \n" . join("|\n  ", (@typeList, @typeListFile)) . "\n)";
 	my $Misordered = "(?x:  \n" . join("|\n  ", @typeListMisordered) . "\n)";
 	my $allWithAttr = "(?x:  \n" . join("|\n  ", @typeListWithAttr) . "\n)";