| Message ID | 20250507181615.1947159-2-kees@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | stackleak: Support Clang stack depth tracking | expand |
+Cc KCOV maintainers On Wed, 7 May 2025 at 20:16, Kees Cook <kees@kernel.org> wrote: > > While __noinstr already contained __no_sanitize_coverage, it needs to > be added to __init and __head section markings to support the Clang > implementation of CONFIG_STACKLEAK. This is to make sure the stack depth > tracking callback is not executed in unsupported contexts. > > The other sanitizer coverage options (trace-pc and trace-cmp) aren't > needed in __head nor __init either ("We are interested in code coverage > as a function of a syscall inputs"[1]), so this appears safe to disable > for them as well. @ Dmitry, Aleksandr - Will this produce some unwanted side-effects for syzbot? I also think it's safe, but just double checking. > Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/kcov.c?h=v6.14#n179 [1] > Signed-off-by: Kees Cook <kees@kernel.org> Acked-by: Marco Elver <elver@google.com> > --- > Cc: Marco Elver <elver@google.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: <x86@kernel.org> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > Cc: Hou Wenlong <houwenlong.hwl@antgroup.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> > Cc: Luis Chamberlain <mcgrof@kernel.org> > Cc: Sami Tolvanen <samitolvanen@google.com> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Christophe Leroy <christophe.leroy@csgroup.eu> > Cc: <kasan-dev@googlegroups.com> > --- > arch/x86/include/asm/init.h | 2 +- > include/linux/init.h | 4 +++- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h > index 8b1b1abcef15..6bfdaeddbae8 100644 > --- a/arch/x86/include/asm/init.h > +++ b/arch/x86/include/asm/init.h > @@ -5,7 +5,7 @@ > #if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 170000 > #define __head __section(".head.text") __no_sanitize_undefined __no_stack_protector > #else > -#define __head __section(".head.text") __no_sanitize_undefined > +#define __head __section(".head.text") __no_sanitize_undefined __no_sanitize_coverage > #endif > > struct x86_mapping_info { > diff --git a/include/linux/init.h b/include/linux/init.h > index ee1309473bc6..c65a050d52a7 100644 > --- a/include/linux/init.h > +++ b/include/linux/init.h > @@ -49,7 +49,9 @@ > > /* These are for everybody (although not all archs will actually > discard it in modules) */ > -#define __init __section(".init.text") __cold __latent_entropy __noinitretpoline > +#define __init __section(".init.text") __cold __latent_entropy \ > + __noinitretpoline \ > + __no_sanitize_coverage > #define __initdata __section(".init.data") > #define __initconst __section(".init.rodata") > #define __exitdata __section(".exit.data") > -- > 2.34.1 >
On Thu, 8 May 2025 at 14:23, Marco Elver <elver@google.com> wrote: > > +Cc KCOV maintainers > > On Wed, 7 May 2025 at 20:16, Kees Cook <kees@kernel.org> wrote: > > > > While __noinstr already contained __no_sanitize_coverage, it needs to > > be added to __init and __head section markings to support the Clang > > implementation of CONFIG_STACKLEAK. This is to make sure the stack depth > > tracking callback is not executed in unsupported contexts. > > > > The other sanitizer coverage options (trace-pc and trace-cmp) aren't > > needed in __head nor __init either ("We are interested in code coverage > > as a function of a syscall inputs"[1]), so this appears safe to disable > > for them as well. > > @ Dmitry, Aleksandr - Will this produce some unwanted side-effects for > syzbot? I also think it's safe, but just double checking. I do not see any problems with this. > > Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/kcov.c?h=v6.14#n179 [1] > > Signed-off-by: Kees Cook <kees@kernel.org> > > Acked-by: Marco Elver <elver@google.com> > > > --- > > Cc: Marco Elver <elver@google.com> > > Cc: Andrey Konovalov <andreyknvl@gmail.com> > > Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Ingo Molnar <mingo@redhat.com> > > Cc: Borislav Petkov <bp@alien8.de> > > Cc: Dave Hansen <dave.hansen@linux.intel.com> > > Cc: <x86@kernel.org> > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > Cc: Ard Biesheuvel <ardb@kernel.org> > > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > > Cc: Hou Wenlong <houwenlong.hwl@antgroup.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Masahiro Yamada <masahiroy@kernel.org> > > Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> > > Cc: Luis Chamberlain <mcgrof@kernel.org> > > Cc: Sami Tolvanen <samitolvanen@google.com> > > Cc: Arnd Bergmann <arnd@arndb.de> > > Cc: Christophe Leroy <christophe.leroy@csgroup.eu> > > Cc: <kasan-dev@googlegroups.com> > > --- > > arch/x86/include/asm/init.h | 2 +- > > include/linux/init.h | 4 +++- > > 2 files changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h > > index 8b1b1abcef15..6bfdaeddbae8 100644 > > --- a/arch/x86/include/asm/init.h > > +++ b/arch/x86/include/asm/init.h > > @@ -5,7 +5,7 @@ > > #if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 170000 > > #define __head __section(".head.text") __no_sanitize_undefined __no_stack_protector > > #else > > -#define __head __section(".head.text") __no_sanitize_undefined > > +#define __head __section(".head.text") __no_sanitize_undefined __no_sanitize_coverage > > #endif > > > > struct x86_mapping_info { > > diff --git a/include/linux/init.h b/include/linux/init.h > > index ee1309473bc6..c65a050d52a7 100644 > > --- a/include/linux/init.h > > +++ b/include/linux/init.h > > @@ -49,7 +49,9 @@ > > > > /* These are for everybody (although not all archs will actually > > discard it in modules) */ > > -#define __init __section(".init.text") __cold __latent_entropy __noinitretpoline > > +#define __init __section(".init.text") __cold __latent_entropy \ > > + __noinitretpoline \ > > + __no_sanitize_coverage > > #define __initdata __section(".init.data") > > #define __initconst __section(".init.rodata") > > #define __exitdata __section(".exit.data") > > -- > > 2.34.1 > >
diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h index 8b1b1abcef15..6bfdaeddbae8 100644 --- a/arch/x86/include/asm/init.h +++ b/arch/x86/include/asm/init.h @@ -5,7 +5,7 @@ #if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 170000 #define __head __section(".head.text") __no_sanitize_undefined __no_stack_protector #else -#define __head __section(".head.text") __no_sanitize_undefined +#define __head __section(".head.text") __no_sanitize_undefined __no_sanitize_coverage #endif struct x86_mapping_info { diff --git a/include/linux/init.h b/include/linux/init.h index ee1309473bc6..c65a050d52a7 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -49,7 +49,9 @@ /* These are for everybody (although not all archs will actually discard it in modules) */ -#define __init __section(".init.text") __cold __latent_entropy __noinitretpoline +#define __init __section(".init.text") __cold __latent_entropy \ + __noinitretpoline \ + __no_sanitize_coverage #define __initdata __section(".init.data") #define __initconst __section(".init.rodata") #define __exitdata __section(".exit.data")
While __noinstr already contained __no_sanitize_coverage, it needs to be added to __init and __head section markings to support the Clang implementation of CONFIG_STACKLEAK. This is to make sure the stack depth tracking callback is not executed in unsupported contexts. The other sanitizer coverage options (trace-pc and trace-cmp) aren't needed in __head nor __init either ("We are interested in code coverage as a function of a syscall inputs"[1]), so this appears safe to disable for them as well. Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/kcov.c?h=v6.14#n179 [1] Signed-off-by: Kees Cook <kees@kernel.org> --- Cc: Marco Elver <elver@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <x86@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hou Wenlong <houwenlong.hwl@antgroup.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: <kasan-dev@googlegroups.com> --- arch/x86/include/asm/init.h | 2 +- include/linux/init.h | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-)