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Message-ID: <20250701183537.501225-1-briannorris@chromium.org>
Date: Tue, 1 Jul 2025 11:34:00 -0700
From: Brian Norris <briannorris@...omium.org>
To: Andy Whitcroft <apw@...onical.com>,
Joe Perches <joe@...ches.com>
Cc: linux-kernel@...r.kernel.org,
Brian Norris <briannorris@...omium.org>,
Dwaipayan Ray <dwaipayanray1@...il.com>,
Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: [PATCH v3] checkpatch: Check for missing sentinels in ID arrays
All of the ID tables based on <linux/mod_devicetable.h> (of_device_id,
pci_device_id, ...) require their arrays to end in an empty sentinel
value. That's usually spelled with an empty initializer entry (e.g.,
"{}"), but also sometimes with explicit 0 entries, field initializers
(e.g., '.id = ""'), or even a macro entry (like PCMCIA_DEVICE_NULL).
Without a sentinel, device-matching code may read out of bounds.
I've found a number of such bugs in driver reviews, and we even
occasionally commit one to the tree. See commit 5751eee5c620 ("i2c:
nomadik: Add missing sentinel to match table") for example.
Teach checkpatch to find these ID tables, and complain if it looks like
there wasn't a sentinel value.
Test output:
$ git format-patch -1 a0d15cc47f29be6d --stdout | scripts/checkpatch.pl -
ERROR: missing sentinel in ID array
#57: FILE: drivers/i2c/busses/i2c-nomadik.c:1073:
+static const struct of_device_id nmk_i2c_eyeq_match_table[] = {
{
.compatible = "XXXXXXXXXXXXXXXXXX",
.data = (void *)(NMK_I2C_EYEQ_FLAG_32B_BUS | NMK_I2C_EYEQ_FLAG_IS_EYEQ5),
},
};
total: 1 errors, 0 warnings, 66 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or --fix-inplace.
"[PATCH] i2c: nomadik: switch from of_device_is_compatible() to" has style problems, please review.
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
When run across the entire tree (scripts/checkpatch.pl -q --types
MISSING_SENTINEL -f ...), false positives exist:
* where macros are used that hide the table from analysis
(e.g., drivers/gpu/drm/radeon/radeon_drv.c / radeon_PCI_IDS).
There are fewer than 5 of these.
* where such tables are processed correctly via ARRAY_SIZE() (fewer than
5 instances). This is by far not the typical usage of *_device_id
arrays.
* some odd parsing artifacts, where ctx_statement_block() seems to quit
in the middle of a block due to #if/#else/#endif.
Signed-off-by: Brian Norris <briannorris@...omium.org>
---
v1: https://lore.kernel.org/all/20241218232716.3624531-1-briannorris@chromium.org/
Changes in v3:
* actually CC LKML this time (sorry, I accidentally sent v2 directly to
maintainers)
* no other change
Changes in v2:
* add a few ID types I missed (i2c, i3c, ieee1394); this time I parsed:
grep 'struct .*_device_id {' include/linux/mod_devicetable.h
* account for some alternative sentinels (e.g.,
ISAPNP_DEVICE_SINGLE_END)
scripts/checkpatch.pl | 82 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 82 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 664f7b7a622c..cfa7db17fe0b 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -685,6 +685,64 @@ our $tracing_logging_tags = qr{(?xi:
[\.\!:\s]*
)};
+# Device ID types from include/linux/mod_devicetable.h.
+our $dev_id_types = qr{(?x:
+ acpi |
+ ap |
+ apr |
+ auxiliary |
+ bcma |
+ ccw |
+ cdx |
+ coreboot |
+ css |
+ dfl |
+ eisa |
+ fsl_mc |
+ hda |
+ hid |
+ hv_vmbus |
+ i2c |
+ i3c |
+ ieee1394 |
+ input |
+ ipack |
+ isapnp |
+ ishtp |
+ mcb |
+ mdio |
+ mei_cl |
+ mhi |
+ mips_cdmm |
+ of |
+ parisc |
+ pci |
+ pci_epf |
+ pcmcia |
+ platform |
+ pnp |
+ pnp_card |
+ rio |
+ rpmsg |
+ sdio |
+ sdw |
+ serio |
+ slim |
+ spi |
+ spmi |
+ ssam |
+ ssb |
+ tee_client |
+ typec |
+ ulpi |
+ usb |
+ vchiq |
+ vio |
+ virtio |
+ wmi |
+ zorro
+)_device_id};
+
sub edit_distance_min {
my (@arr) = @_;
my $len = scalar @arr;
@@ -7678,6 +7736,30 @@ sub process {
WARN("DUPLICATED_SYSCTL_CONST",
"duplicated sysctl range checking value '$1', consider using the shared one in include/linux/sysctl.h\n" . $herecurr);
}
+
+# Check that *_device_id tables have sentinel entries.
+ if (defined $stat && $line =~ /struct $dev_id_types .*\[\] = \{/) {
+ my $stripped = $stat;
+
+ # Strip diff line prefixes.
+ $stripped =~ s/(^|\n)./$1/g;
+ # Line continuations.
+ $stripped =~ s/\\\n/\n/g;
+ # Strip whitespace, empty strings, zeroes, and commas.
+ $stripped =~ s/""//g;
+ $stripped =~ s/0x0//g;
+ $stripped =~ s/[\s$;,0]//g;
+ # Strip field assignments.
+ $stripped =~ s/\.$Ident=//g;
+
+ if (!(substr($stripped, -4) eq "{}};" ||
+ substr($stripped, -6) eq "{{}}};" ||
+ $stripped =~ /PCMCIA_DEVICE_NULL};$/ ||
+ $stripped =~ /ISAPNP_DEVICE_SINGLE_END}};$/ ||
+ $stripped =~ /ISAPNP_CARD_END}};$/)) {
+ ERROR("MISSING_SENTINEL", "missing sentinel in ID array\n" . "$here\n$stat\n");
+ }
+ }
}
# If we have no input at all, then there is nothing to report on
--
2.50.0.727.gbf7dc18ff4-goog
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