From e79302ae8c8cceb51cf642d5ace9da02668cb7b4 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 2 Jun 2020 17:04:03 +0200 Subject: kcsan: Remove __no_kcsan_or_inline There are no more user of this function attribute, also, with us now actively supporting '__no_kcsan inline' it doesn't make sense to have in any case. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/compiler_types.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 21aed0981edf..938249809511 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -193,10 +193,7 @@ struct ftrace_likely_data { #define __no_kcsan __no_sanitize_thread #ifdef __SANITIZE_THREAD__ -# define __no_kcsan_or_inline __no_kcsan notrace __maybe_unused -# define __no_sanitize_or_inline __no_kcsan_or_inline -#else -# define __no_kcsan_or_inline __always_inline +# define __no_sanitize_or_inline __no_kcsan notrace __maybe_unused #endif #ifndef __no_sanitize_or_inline -- cgit v1.2.3 From 5ddbc4082e1072eeeae52ff561a88620a05be08f Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 2 Jun 2020 18:47:11 +0200 Subject: x86, kcsan: Add __no_kcsan to noinstr The 'noinstr' function attribute means no-instrumentation, this should very much include *SAN. Because lots of that is broken at present, only include KCSAN for now, as that is limited to clang11, which has sane function attribute behaviour. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/compiler_types.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 938249809511..a8b4266084a1 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -118,10 +118,6 @@ struct ftrace_likely_data { #define notrace __attribute__((__no_instrument_function__)) #endif -/* Section for code which can't be instrumented at all */ -#define noinstr \ - noinline notrace __attribute((__section__(".noinstr.text"))) - /* * it doesn't make sense on ARM (currently the only user of __naked) * to trace naked functions because then mcount is called without @@ -200,6 +196,10 @@ struct ftrace_likely_data { #define __no_sanitize_or_inline __always_inline #endif +/* Section for code which can't be instrumented at all */ +#define noinstr \ + noinline notrace __attribute((__section__(".noinstr.text"))) __no_kcsan + #endif /* __KERNEL__ */ #endif /* __ASSEMBLY__ */ -- cgit v1.2.3 From 5144f8a8dfd7b3681f0a2b5bf599a210b2315018 Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Thu, 4 Jun 2020 07:58:11 +0200 Subject: compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr Adds the portable definitions for __no_sanitize_address, and __no_sanitize_undefined, and subsequently changes noinstr to use the attributes to disable instrumentation via KASAN or UBSAN. Reported-by: syzbot+dc1fa714cb070b184db5@syzkaller.appspotmail.com Signed-off-by: Marco Elver Signed-off-by: Peter Zijlstra (Intel) Acked-by: Miguel Ojeda Link: https://lore.kernel.org/lkml/000000000000d2474c05a6c938fe@google.com/ --- include/linux/compiler-clang.h | 8 ++++++++ include/linux/compiler-gcc.h | 6 ++++++ include/linux/compiler_types.h | 3 ++- 3 files changed, 16 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index ee37256ec8bd..5e55302e3bf6 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -33,6 +33,14 @@ #define __no_sanitize_thread #endif +#if __has_feature(undefined_behavior_sanitizer) +/* GCC does not have __SANITIZE_UNDEFINED__ */ +#define __no_sanitize_undefined \ + __attribute__((no_sanitize("undefined"))) +#else +#define __no_sanitize_undefined +#endif + /* * Not all versions of clang implement the the type-generic versions * of the builtin overflow checkers. Fortunately, clang implements diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 7dd4e0349ef3..1c74464c80c6 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -150,6 +150,12 @@ #define __no_sanitize_thread #endif +#if __has_attribute(__no_sanitize_undefined__) +#define __no_sanitize_undefined __attribute__((no_sanitize_undefined)) +#else +#define __no_sanitize_undefined +#endif + #if GCC_VERSION >= 50100 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 #endif diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index a8b4266084a1..85b8d2370c24 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -198,7 +198,8 @@ struct ftrace_likely_data { /* Section for code which can't be instrumented at all */ #define noinstr \ - noinline notrace __attribute((__section__(".noinstr.text"))) __no_kcsan + noinline notrace __attribute((__section__(".noinstr.text"))) \ + __no_kcsan __no_sanitize_address __no_sanitize_undefined #endif /* __KERNEL__ */ -- cgit v1.2.3 From 6b643a07a7e41f9e11cfbb9bba4c5c9791ac2997 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 3 Jun 2020 20:09:06 +0200 Subject: x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*() The UBSAN instrumentation only inserts external CALLs when things go 'BAD', much like WARN(). So treat them similar to WARN()s for noinstr, that is: allow them, at the risk of taking the machine down, to get their message out. Suggested-by: Marco Elver Signed-off-by: Peter Zijlstra (Intel) Acked-by: Marco Elver --- include/linux/compiler_types.h | 2 +- tools/objtool/check.c | 28 +++++++++++++++++++++++++++- 2 files changed, 28 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 85b8d2370c24..14513e88b7e0 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -199,7 +199,7 @@ struct ftrace_likely_data { /* Section for code which can't be instrumented at all */ #define noinstr \ noinline notrace __attribute((__section__(".noinstr.text"))) \ - __no_kcsan __no_sanitize_address __no_sanitize_undefined + __no_kcsan __no_sanitize_address #endif /* __KERNEL__ */ diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 5fbb90a80d23..3e214f879ada 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2190,10 +2190,36 @@ static inline const char *call_dest_name(struct instruction *insn) return "{dynamic}"; } +static inline bool noinstr_call_dest(struct symbol *func) +{ + /* + * We can't deal with indirect function calls at present; + * assume they're instrumented. + */ + if (!func) + return false; + + /* + * If the symbol is from a noinstr section; we good. + */ + if (func->sec->noinstr) + return true; + + /* + * The __ubsan_handle_*() calls are like WARN(), they only happen when + * something 'BAD' happened. At the risk of taking the machine down, + * let them proceed to get the message out. + */ + if (!strncmp(func->name, "__ubsan_handle_", 15)) + return true; + + return false; +} + static int validate_call(struct instruction *insn, struct insn_state *state) { if (state->noinstr && state->instr <= 0 && - (!insn->call_dest || !insn->call_dest->sec->noinstr)) { + !noinstr_call_dest(insn->call_dest)) { WARN_FUNC("call to %s() leaves .noinstr.text section", insn->sec, insn->offset, call_dest_name(insn)); return 1; -- cgit v1.2.3 From 33aea07f30c261eff7ba229f19fd1b161e0fb851 Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Tue, 16 Jun 2020 01:15:29 +0200 Subject: compiler_attributes.h: Support no_sanitize_undefined check with GCC 4 UBSAN is supported since GCC 4.9, which unfortunately did not yet have __has_attribute(). To work around, the __GCC4_has_attribute workaround requires defining which compiler version supports the given attribute. In the case of no_sanitize_undefined, it is the first version that supports UBSAN, which is GCC 4.9. Reported-by: kernel test robot Signed-off-by: Marco Elver Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miguel Ojeda Link: https://lkml.kernel.org/r/20200615231529.GA119644@google.com --- include/linux/compiler_attributes.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index cdf016596659..c8f03d2969df 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -40,6 +40,7 @@ # define __GCC4_has_attribute___noclone__ 1 # define __GCC4_has_attribute___nonstring__ 0 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8) +# define __GCC4_has_attribute___no_sanitize_undefined__ (__GNUC_MINOR__ >= 9) # define __GCC4_has_attribute___fallthrough__ 0 #endif -- cgit v1.2.3