From: Brian Norris Date: Wed, 2 Jul 2025 23:52:00 +0000 (-0700) Subject: checkpatch: check for missing sentinels in ID arrays X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=22c2ed6996ac34df506040a069fac3e5100b5c0e;p=thirdparty%2Flinux.git checkpatch: check for missing sentinels in ID arrays All of the ID tables based on (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. Also, not every "struct *_device_id" is in fact a sentinel-requiring structure, but even with such types, false positives are very rare. Link: https://lkml.kernel.org/r/20250702235245.1007351-1-briannorris@chromium.org Signed-off-by: Brian Norris Acked-by: Joe Perches Cc: Andy Whitcroft Cc: Brian Norris Cc: Dwaipayan Ray Cc: Lukas Bulwahn Signed-off-by: Andrew Morton --- diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 489b74d52abe7..d4c24318548c7 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -685,6 +685,9 @@ our $tracing_logging_tags = qr{(?xi: [\.\!:\s]* )}; +# Device ID types like found in include/linux/mod_devicetable.h. +our $dev_id_types = qr{\b[a-z]\w*_device_id\b}; + sub edit_distance_min { my (@arr) = @_; my $len = scalar @arr; @@ -7679,6 +7682,31 @@ 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 && $line =~ /struct\s+$dev_id_types\s+\w+\s*\[\s*\]\s*=\s*\{/) { + 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 "{{}}};" || + $stripped =~ /ISAPNP_DEVICE_SINGLE_END}};$/ || + $stripped =~ /ISAPNP_CARD_END}};$/ || + $stripped =~ /NULL};$/ || + $stripped =~ /PCMCIA_DEVICE_NULL};$/)) { + 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