2022-02-01 11:23:27

by Kees Cook

Subject: [PATCH] fortify: Update compile-time tests for Clang 14

Clang 14 introduces support for compiletime_assert(). Update the
compile-time warning regex to catch Clang's variant of the warning text
in preparation for Clang supporting CONFIG_FORTIFY_SOURCE.

Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
I'm splitting this patch out of the main Clang FORTIFY enabling patch.
---
scripts/test_fortify.sh | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/scripts/test_fortify.sh b/scripts/test_fortify.sh
index a4da365508f0..c2688ab8281d 100644
--- a/scripts/test_fortify.sh
+++ b/scripts/test_fortify.sh
@@ -46,8 +46,12 @@ if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then
status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN"
fi
else
- # If the build failed, check for the warning in the stderr (gcc).
- if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then
+ # If the build failed, check for the warning in the stderr.
+ # GCC:
+ # ./include/linux/fortify-string.h:316:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
+ # Clang 14:
+ # ./include/linux/fortify-string.h:316:4: error: call to __write_overflow_field declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
+ if ! grep -Eq -m1 "error: call to .?\b${WANT}\b.?" "$TMP" ; then
status="warning: unsafe ${FUNC}() usage lacked '$WANT' warning in $IN"
fi
fi
--
2.30.2

2022-02-01 15:00:53

by Nathan Chancellor

Subject: Re: [PATCH] fortify: Update compile-time tests for Clang 14

On Sun, Jan 30, 2022 at 10:16:16AM -0800, Kees Cook wrote:
> Clang 14 introduces support for compiletime_assert(). Update the
> compile-time warning regex to catch Clang's variant of the warning text
> in preparation for Clang supporting CONFIG_FORTIFY_SOURCE.
>
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>

Reviewed-by: Nathan Chancellor <[email protected]>

> ---
> I'm splitting this patch out of the main Clang FORTIFY enabling patch.
> ---
> scripts/test_fortify.sh | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/test_fortify.sh b/scripts/test_fortify.sh
> index a4da365508f0..c2688ab8281d 100644
> --- a/scripts/test_fortify.sh
> +++ b/scripts/test_fortify.sh
> @@ -46,8 +46,12 @@ if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then
> status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN"
> fi
> else
> - # If the build failed, check for the warning in the stderr (gcc).
> - if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then
> + # If the build failed, check for the warning in the stderr.
> + # GCC:
> + # ./include/linux/fortify-string.h:316:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
> + # Clang 14:
> + # ./include/linux/fortify-string.h:316:4: error: call to __write_overflow_field declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> + if ! grep -Eq -m1 "error: call to .?\b${WANT}\b.?" "$TMP" ; then
> status="warning: unsafe ${FUNC}() usage lacked '$WANT' warning in $IN"
> fi
> fi
> --
> 2.30.2
>

2022-02-01 20:49:31

by Nick Desaulniers

Subject: Re: [PATCH] fortify: Update compile-time tests for Clang 14

On Sun, Jan 30, 2022 at 10:16 AM Kees Cook <[email protected]> wrote:
>
> Clang 14 introduces support for compiletime_assert(). Update the
> compile-time warning regex to catch Clang's variant of the warning text
> in preparation for Clang supporting CONFIG_FORTIFY_SOURCE.

https://twitter.com/ifosteve/status/1190348262500421634?lang=en
error messages can change over time. More thoughts below.

>
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> I'm splitting this patch out of the main Clang FORTIFY enabling patch.
> ---
> scripts/test_fortify.sh | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/test_fortify.sh b/scripts/test_fortify.sh
> index a4da365508f0..c2688ab8281d 100644
> --- a/scripts/test_fortify.sh
> +++ b/scripts/test_fortify.sh
> @@ -46,8 +46,12 @@ if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then
> status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN"
> fi
> else
> - # If the build failed, check for the warning in the stderr (gcc).
> - if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then
> + # If the build failed, check for the warning in the stderr.
> + # GCC:
> + # ./include/linux/fortify-string.h:316:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
> + # Clang 14:
> + # ./include/linux/fortify-string.h:316:4: error: call to __write_overflow_field declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> + if ! grep -Eq -m1 "error: call to .?\b${WANT}\b.?" "$TMP" ; then

Doesn't this depend on -Werror being set? I guess it did so before
hand, too, but couldn't I unset CONFIG_WERROR then this check would
still fail (since instead of `error:` we'd have `warning:`)? If we
used __attribute__((error(""))) then this would always be an error.
Right now, it is only because -Werror is set promoting the warning
diagnostic to an error.

> status="warning: unsafe ${FUNC}() usage lacked '$WANT' warning in $IN"
> fi
> fi
> --
> 2.30.2
>


--
Thanks,
~Nick Desaulniers

2022-02-01 20:51:46

by Kees Cook

Subject: Re: [PATCH] fortify: Update compile-time tests for Clang 14

On Mon, Jan 31, 2022 at 11:09:27AM -0800, Nick Desaulniers wrote:
> On Sun, Jan 30, 2022 at 10:16 AM Kees Cook <[email protected]> wrote:
> >
> > Clang 14 introduces support for compiletime_assert(). Update the
> > compile-time warning regex to catch Clang's variant of the warning text
> > in preparation for Clang supporting CONFIG_FORTIFY_SOURCE.
>
> https://twitter.com/ifosteve/status/1190348262500421634?lang=en
> error messages can change over time. More thoughts below.

Sure, but I don't want the compile-time checks to silently regress,
which requires looking specifically for the error.

> > Cc: Nathan Chancellor <[email protected]>
> > Cc: Nick Desaulniers <[email protected]>
> > Cc: [email protected]
> > Cc: [email protected]
> > Signed-off-by: Kees Cook <[email protected]>
> > ---
> > I'm splitting this patch out of the main Clang FORTIFY enabling patch.
> > ---
> > scripts/test_fortify.sh | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/scripts/test_fortify.sh b/scripts/test_fortify.sh
> > index a4da365508f0..c2688ab8281d 100644
> > --- a/scripts/test_fortify.sh
> > +++ b/scripts/test_fortify.sh
> > @@ -46,8 +46,12 @@ if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then
> > status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN"
> > fi
> > else
> > - # If the build failed, check for the warning in the stderr (gcc).
> > - if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then
> > + # If the build failed, check for the warning in the stderr.
> > + # GCC:
> > + # ./include/linux/fortify-string.h:316:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
> > + # Clang 14:
> > + # ./include/linux/fortify-string.h:316:4: error: call to __write_overflow_field declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> > + if ! grep -Eq -m1 "error: call to .?\b${WANT}\b.?" "$TMP" ; then
>
> Doesn't this depend on -Werror being set? I guess it did so before
> hand, too, but couldn't I unset CONFIG_WERROR then this check would
> still fail (since instead of `error:` we'd have `warning:`)? If we
> used __attribute__((error(""))) then this would always be an error.
> Right now, it is only because -Werror is set promoting the warning
> diagnostic to an error.

Right, see earlier up in the script. "-Werror" is explicitly set:

line 40: if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then

--
Kees Cook

2022-02-01 20:51:57

by Nick Desaulniers

Subject: Re: [PATCH] fortify: Update compile-time tests for Clang 14

On Mon, Jan 31, 2022 at 1:09 PM Kees Cook <[email protected]> wrote:
>
> On Mon, Jan 31, 2022 at 11:09:27AM -0800, Nick Desaulniers wrote:
> > On Sun, Jan 30, 2022 at 10:16 AM Kees Cook <[email protected]> wrote:
> > >
> > > Clang 14 introduces support for compiletime_assert(). Update the
> > > compile-time warning regex to catch Clang's variant of the warning text
> > > in preparation for Clang supporting CONFIG_FORTIFY_SOURCE.
> >
> > https://twitter.com/ifosteve/status/1190348262500421634?lang=en
> > error messages can change over time. More thoughts below.
>
> Sure, but I don't want the compile-time checks to silently regress,
> which requires looking specifically for the error.
>
> > > Cc: Nathan Chancellor <[email protected]>
> > > Cc: Nick Desaulniers <[email protected]>
> > > Cc: [email protected]
> > > Cc: [email protected]
> > > Signed-off-by: Kees Cook <[email protected]>
> > > ---
> > > I'm splitting this patch out of the main Clang FORTIFY enabling patch.
> > > ---
> > > scripts/test_fortify.sh | 8 ++++++--
> > > 1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/scripts/test_fortify.sh b/scripts/test_fortify.sh
> > > index a4da365508f0..c2688ab8281d 100644
> > > --- a/scripts/test_fortify.sh
> > > +++ b/scripts/test_fortify.sh
> > > @@ -46,8 +46,12 @@ if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then
> > > status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN"
> > > fi
> > > else
> > > - # If the build failed, check for the warning in the stderr (gcc).
> > > - if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then
> > > + # If the build failed, check for the warning in the stderr.
> > > + # GCC:
> > > + # ./include/linux/fortify-string.h:316:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
> > > + # Clang 14:
> > > + # ./include/linux/fortify-string.h:316:4: error: call to __write_overflow_field declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> > > + if ! grep -Eq -m1 "error: call to .?\b${WANT}\b.?" "$TMP" ; then
> >
> > Doesn't this depend on -Werror being set? I guess it did so before
> > hand, too, but couldn't I unset CONFIG_WERROR then this check would
> > still fail (since instead of `error:` we'd have `warning:`)? If we
> > used __attribute__((error(""))) then this would always be an error.
> > Right now, it is only because -Werror is set promoting the warning
> > diagnostic to an error.
>
> Right, see earlier up in the script. "-Werror" is explicitly set:
>
> line 40: if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then

Yep, I missed that.
Reviewed-by: Nick Desaulniers <[email protected]>

>
> --
> Kees Cook



--
Thanks,
~Nick Desaulniers