| Message ID | 20230517204530.never.151-kees@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | checkpatch: Warn about 0-length and 1-element arrays | expand |
* On Wed, 2023-05-17 at 13:45 -0700, Kees Cook wrote: > Fake flexible arrays have been deprecated since last millennium. Proper > C99 flexible arrays must be used throughout the kernel so > CONFIG_FORTIFY_SOURCE and CONFIG_UBSAN_BOUNDS can provide proper array > bounds checking. I don't think this does what you want. After adding this patch to checkpatch with this diff: No warning ----------------------- diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 4f4f79532c6cf..513cb102b3b38 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -73,6 +73,11 @@ static DEFINE_SPINLOCK(target_list_lock); */ static struct console netconsole_ext; +struct foobar { + int a; + int b[1]; +}; + /** * struct netconsole_target - Represents a configured netconsole target. * @list: Links this target into the target_list. ----------------------- because $context_function is DEFINE_SPINLOCK I think you want something like: --- scripts/checkpatch.pl | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index b30114d637c40..778a0808c37cf 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -7418,6 +7418,18 @@ sub process { } } + # check for array definition/declarations that should use flexible arrays instead + if ($sline =~ /^[\+ ]\s*}\s*;\s*$/ && + $prevline =~ /^\+\s*$Type\s*$Ident\s*\[\s*(0|1)\s*\]\s*;\s*$/) { + if ($1 =~ '0') { + WARN("ZERO_LENGTH_ARRAY", + "Prefer C99 flexible arrays instead of zero-length arrays - see https://github.com/KSPP/linux/issues/78\n" . $hereprev); + } else { + WARN("ONE_ELEMENT_ARRAY", + "Prefer C99 flexible arrays instead of one-element arrays - see https://github.com/KSPP/linux/issues/79\n" . $hereprev); + } + } + # nested likely/unlikely calls if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { WARN("LIKELY_MISUSE",
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index a90e0ede53ad..415b3c14589b 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -7430,6 +7430,20 @@ sub process { } } +# check for fake flexible array declarations (i.e. not in function scope) + if (!defined($context_function)) { + if ($line =~ /^\+\s*((struct|union|enum)\s+$Ident|$Type|})\s+$Ident\s*\[0\][^;]*;/) { + if (WARN("ZERO_LENGTH_ARRAY", + "Use C99 flexible arrays instead of zero-length arrays - see https://github.com/KSPP/linux/issues/78\n" . $herecurr) && $fix) { + $fixed[$fixlinenr] =~ s/\[0\]/[]/g; + } + } + if ($line =~ /^\+\s*((struct|union|enum)\s+$Ident|$Type|})\s+$Ident\s*\[1\][^;]*;/) { + WARN("ONE_ELEMENT_ARRAY", + "Use C99 flexible arrays instead of one-element arrays - see https://github.com/KSPP/linux/issues/79\n" . $herecurr); + } + } + # nested likely/unlikely calls if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { WARN("LIKELY_MISUSE",
Fake flexible arrays have been deprecated since last millennium. Proper C99 flexible arrays must be used throughout the kernel so CONFIG_FORTIFY_SOURCE and CONFIG_UBSAN_BOUNDS can provide proper array bounds checking. Cc: Andy Whitcroft <apw@canonical.com> Cc: Joe Perches <joe@perches.com> Cc: Dwaipayan Ray <dwaipayanray1@gmail.com> Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> --- I couldn't find a better way to figure out if a patch line is part of a structure definition. I'm open to ideas! e.g. this would have caught commit f5823fe6897c. --- scripts/checkpatch.pl | 14 ++++++++++++++ 1 file changed, 14 insertions(+)