| Message ID | 20240123002814.1396804-69-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | overflow: Refactor open-coded arithmetic wrap-around | expand |
On 23/01/24 02:27, Kees Cook wrote: > In an effort to separate intentional arithmetic wrap-around from > unexpected wrap-around, we need to refactor places that depend on this > kind of math. One of the most common code patterns of this is: > > VAR + value < VAR > > Notably, this is considered "undefined behavior" for signed and pointer > types, which the kernel works around by using the -fno-strict-overflow > option in the build[1] (which used to just be -fwrapv). Regardless, we > want to get the kernel source to the position where we can meaningfully > instrument arithmetic wrap-around conditions and catch them when they > are unexpected, regardless of whether they are signed[2], unsigned[3], > or pointer[4] types. > > Refactor open-coded wrap-around addition test to use add_would_overflow(). > This paves the way to enabling the wrap-around sanitizers in the future. > > Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] > Link: https://github.com/KSPP/linux/issues/26 [2] > Link: https://github.com/KSPP/linux/issues/27 [3] > Link: https://github.com/KSPP/linux/issues/344 [4] > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Arnaldo Carvalho de Melo <acme@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Cc: Jiri Olsa <jolsa@kernel.org> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Ian Rogers <irogers@google.com> > Cc: Adrian Hunter <adrian.hunter@intel.com> > Cc: John Garry <john.garry@huawei.com> > Cc: Fangrui Song <maskray@google.com> > Cc: linux-perf-users@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > tools/perf/util/dso.c | 2 +- > tools/perf/util/unwind-libdw.c | 2 +- > tools/perf/util/unwind-libunwind-local.c | 2 +- > 3 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c > index 22fd5fa806ed..470a86f1cdfd 100644 > --- a/tools/perf/util/dso.c > +++ b/tools/perf/util/dso.c > @@ -1122,7 +1122,7 @@ static ssize_t data_read_write_offset(struct dso *dso, struct machine *machine, > if (offset > dso->data.file_size) > return -1; > > - if (offset + size < offset) > + if (add_would_overflow(offset, size)) perf tools has separate includes to the kernel, so does not seem to include add_would_overflow() in any of its include files at this point. Need to update tools/include/linux/overflow.h first.
On Tue, Jan 23, 2024 at 08:21:41AM +0200, Adrian Hunter wrote: > perf tools has separate includes to the kernel, so does not > seem to include add_would_overflow() in any of its include > files at this point. Need to update > tools/include/linux/overflow.h first. Oops, thank you! I will adjust this.
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index 22fd5fa806ed..470a86f1cdfd 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -1122,7 +1122,7 @@ static ssize_t data_read_write_offset(struct dso *dso, struct machine *machine, if (offset > dso->data.file_size) return -1; - if (offset + size < offset) + if (add_would_overflow(offset, size)) return -1; return cached_io(dso, machine, offset, data, size, out); diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c index 6013335a8dae..45a89cbb2c8d 100644 --- a/tools/perf/util/unwind-libdw.c +++ b/tools/perf/util/unwind-libdw.c @@ -198,7 +198,7 @@ static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word * end = start + stack->size; /* Check overflow. */ - if (addr + sizeof(Dwarf_Word) < addr) + if (add_would_overflow(addr, sizeof(Dwarf_Word))) return false; if (addr < start || addr + sizeof(Dwarf_Word) > end) { diff --git a/tools/perf/util/unwind-libunwind-local.c b/tools/perf/util/unwind-libunwind-local.c index dac536e28360..ac71cc7f53b9 100644 --- a/tools/perf/util/unwind-libunwind-local.c +++ b/tools/perf/util/unwind-libunwind-local.c @@ -587,7 +587,7 @@ static int access_mem(unw_addr_space_t __maybe_unused as, end = start + stack->size; /* Check overflow. */ - if (addr + sizeof(unw_word_t) < addr) + if (add_would_overflow(addr, sizeof(unw_word_t))) return -EINVAL; if (addr < start || addr + sizeof(unw_word_t) >= end) {
In an effort to separate intentional arithmetic wrap-around from unexpected wrap-around, we need to refactor places that depend on this kind of math. One of the most common code patterns of this is: VAR + value < VAR Notably, this is considered "undefined behavior" for signed and pointer types, which the kernel works around by using the -fno-strict-overflow option in the build[1] (which used to just be -fwrapv). Regardless, we want to get the kernel source to the position where we can meaningfully instrument arithmetic wrap-around conditions and catch them when they are unexpected, regardless of whether they are signed[2], unsigned[3], or pointer[4] types. Refactor open-coded wrap-around addition test to use add_would_overflow(). This paves the way to enabling the wrap-around sanitizers in the future. Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] Link: https://github.com/KSPP/linux/issues/26 [2] Link: https://github.com/KSPP/linux/issues/27 [3] Link: https://github.com/KSPP/linux/issues/344 [4] Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: John Garry <john.garry@huawei.com> Cc: Fangrui Song <maskray@google.com> Cc: linux-perf-users@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- tools/perf/util/dso.c | 2 +- tools/perf/util/unwind-libdw.c | 2 +- tools/perf/util/unwind-libunwind-local.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-)