Messages in this thread | | | From | Ian Rogers <> | Date | Fri, 20 Mar 2020 11:25:47 -0700 | Subject | Re: [PATCH] perf mem2node: avoid double free related to realloc |
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On Sun, Mar 15, 2020 at 2:30 AM Jiri Olsa <jolsa@redhat.com> wrote: > > On Sat, Mar 14, 2020 at 09:49:37AM -0700, Ian Rogers wrote: > > On Sat, Mar 14, 2020 at 7:23 AM Jiri Olsa <jolsa@redhat.com> wrote: > > > > > > On Fri, Mar 13, 2020 at 09:28:26PM -0700, Ian Rogers wrote: > > > > Realloc of size zero is a free not an error, avoid this causing a double > > > > free. Caught by clang's address sanitizer: > > > > > > > > ==2634==ERROR: AddressSanitizer: attempting double-free on 0x6020000015f0 in thread T0: > > > > #0 0x5649659297fd in free llvm/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:123:3 > > > > #1 0x5649659e9251 in __zfree tools/lib/zalloc.c:13:2 > > > > #2 0x564965c0f92c in mem2node__exit tools/perf/util/mem2node.c:114:2 > > > > #3 0x564965a08b4c in perf_c2c__report tools/perf/builtin-c2c.c:2867:2 > > > > #4 0x564965a0616a in cmd_c2c tools/perf/builtin-c2c.c:2989:10 > > > > #5 0x564965944348 in run_builtin tools/perf/perf.c:312:11 > > > > #6 0x564965943235 in handle_internal_command tools/perf/perf.c:364:8 > > > > #7 0x5649659440c4 in run_argv tools/perf/perf.c:408:2 > > > > #8 0x564965942e41 in main tools/perf/perf.c:538:3 > > > > > > > > 0x6020000015f0 is located 0 bytes inside of 1-byte region [0x6020000015f0,0x6020000015f1) > > > > freed by thread T0 here: > > > > #0 0x564965929da3 in realloc third_party/llvm/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3 > > > > #1 0x564965c0f55e in mem2node__init tools/perf/util/mem2node.c:97:16 > > > > #2 0x564965a08956 in perf_c2c__report tools/perf/builtin-c2c.c:2803:8 > > > > #3 0x564965a0616a in cmd_c2c tools/perf/builtin-c2c.c:2989:10 > > > > #4 0x564965944348 in run_builtin tools/perf/perf.c:312:11 > > > > #5 0x564965943235 in handle_internal_command tools/perf/perf.c:364:8 > > > > #6 0x5649659440c4 in run_argv tools/perf/perf.c:408:2 > > > > #7 0x564965942e41 in main tools/perf/perf.c:538:3 > > > > > > > > previously allocated by thread T0 here: > > > > #0 0x564965929c42 in calloc third_party/llvm/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:154:3 > > > > #1 0x5649659e9220 in zalloc tools/lib/zalloc.c:8:9 > > > > #2 0x564965c0f32d in mem2node__init tools/perf/util/mem2node.c:61:12 > > > > #3 0x564965a08956 in perf_c2c__report tools/perf/builtin-c2c.c:2803:8 > > > > #4 0x564965a0616a in cmd_c2c tools/perf/builtin-c2c.c:2989:10 > > > > #5 0x564965944348 in run_builtin tools/perf/perf.c:312:11 > > > > #6 0x564965943235 in handle_internal_command tools/perf/perf.c:364:8 > > > > #7 0x5649659440c4 in run_argv tools/perf/perf.c:408:2 > > > > #8 0x564965942e41 in main tools/perf/perf.c:538:3 > > > > > > > > Signed-off-by: Ian Rogers <irogers@google.com> > > > > --- > > > > tools/perf/util/mem2node.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/tools/perf/util/mem2node.c b/tools/perf/util/mem2node.c > > > > index 797d86a1ab09..7f97aa69eb65 100644 > > > > --- a/tools/perf/util/mem2node.c > > > > +++ b/tools/perf/util/mem2node.c > > > > @@ -95,7 +95,7 @@ int mem2node__init(struct mem2node *map, struct perf_env *env) > > > > > > > > /* Cut unused entries, due to merging. */ > > > > tmp_entries = realloc(entries, sizeof(*entries) * j); > > > > - if (tmp_entries) > > > > + if (j == 0 || tmp_entries) > > > > > > nice catch.. I wonder if we should fail in here, or at least > > > warn that there're no entris.. which is really strange ;-) > > > > The workload was the stream benchmark with perf c2c, but stream isn't > > particularly long running. Not sure how j became 0, there's 2 > > possibilities in the code. The worry with a warning is the spam, so I > > just wanted to make the code correct. > > I was wondering if we should fail completely, > but we might break some c2c expected behaviour > > how about just WARN_ONCE pn j == 0, and then > the lookup will fail already with: > > if (WARN_ONCE(node < 0, "WARNING: failed to find node\n")) > return; > > just get enough hints ;-)
Sorry for the delay. I sent a v2 hopefully doing what you asked :-) https://lkml.org/lkml/2020/3/20/858
Thanks, Ian
> jirka > > > > > Thanks, > > Ian > > > > > thanks, > > > jirka > > > > > > > entries = tmp_entries; > > > > > > > > for (i = 0; i < j; i++) { > > > > -- > > > > 2.25.1.481.gfbce0eb801-goog > > > > > > > > > >
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