Messages in this thread Patch in this message | | | From | 平松雅巳 / HIRAMATU,MASAMI <> | Subject | RE: [PATCH 1/2] perf probe: Prevent segfault when reading probe point with absolute address | Date | Wed, 26 Aug 2015 00:08:07 +0000 |
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> From: Wang Nan [mailto:wangnan0@huawei.com] > > 'perf probe -l' panic if there is a manually inserted probing point > with absolute address. For example: > > # echo 'p:probe/abs_ffffffff811e6615 0xffffffff811e6615' > /sys/kernel/debug/tracing/kprobe_events > # perf probe -l > Segmentation fault (core dumped) > > This patch fix this problem by considering the situation that > "tp->symbol == NULL" in find_perf_probe_point_from_dwarf() and > find_perf_probe_point_from_map().
Oops, OK this is a bug.
Thanks!
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> > After this patch: > > # perf probe -l > probe:abs_ffffffff811e6615 (on SyS_write+5@fs/read_write.c) > > And when debug info is missing: > > # rm -rf ~/.debug > # mv /lib/modules/4.2.0-rc1+/build/vmlinux /lib/modules/4.2.0-rc1+/build/vmlinux.bak > # perf probe -l > probe:abs_ffffffff811e6615 (on sys_write+5) > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > Cc: Arnaldo Carvalho de Melo <acme@kernel.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Cc: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/util/probe-event.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c > index f07374b..6c7e538 100644 > --- a/tools/perf/util/probe-event.c > +++ b/tools/perf/util/probe-event.c > @@ -515,7 +515,7 @@ static int find_perf_probe_point_from_dwarf(struct probe_trace_point *tp, > if (ret < 0) > goto error; > addr += stext; > - } else { > + } else if (tp->symbol) { > addr = kernel_get_symbol_address_by_name(tp->symbol, false); > if (addr == 0) > goto error; > @@ -1815,17 +1815,17 @@ static int find_perf_probe_point_from_map(struct probe_trace_point *tp, > { > struct symbol *sym = NULL; > struct map *map; > - u64 addr; > + u64 addr = tp->address; > int ret = -ENOENT; > > if (!is_kprobe) { > map = dso__new_map(tp->module); > if (!map) > goto out; > - addr = tp->address; > sym = map__find_symbol(map, addr, NULL); > } else { > - addr = kernel_get_symbol_address_by_name(tp->symbol, true); > + if (tp->symbol) > + addr = kernel_get_symbol_address_by_name(tp->symbol, true); > if (addr) { > addr += tp->offset; > sym = __find_kernel_function(addr, &map); > -- > 1.8.3.4
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