From 3e70008a6021fffd2cd1614734603ea970773060 Mon Sep 17 00:00:00 2001 From: Leo Yan Date: Fri, 9 Aug 2019 18:47:52 +0800 Subject: [PATCH] perf trace: Fix segmentation fault when access syscall info on arm64 'perf trace' reports the segmentation fault as below on Arm64: # perf trace -e string -e augmented_raw_syscalls.c LLVM: dumping tools/perf/examples/bpf/augmented_raw_syscalls.o perf: Segmentation fault Obtained 12 stack frames. perf(sighandler_dump_stack+0x47) [0xaaaaac96ac87] linux-vdso.so.1(+0x5b7) [0xffffadbeb5b7] /lib/aarch64-linux-gnu/libc.so.6(strlen+0x10) [0xfffface7d5d0] /lib/aarch64-linux-gnu/libc.so.6(_IO_vfprintf+0x1ac7) [0xfffface49f97] /lib/aarch64-linux-gnu/libc.so.6(__vsnprintf_chk+0xc7) [0xffffacedfbe7] perf(scnprintf+0x97) [0xaaaaac9ca3ff] perf(+0x997bb) [0xaaaaac8e37bb] perf(cmd_trace+0x28e7) [0xaaaaac8ec09f] perf(+0xd4a13) [0xaaaaac91ea13] perf(main+0x62f) [0xaaaaac8a147f] /lib/aarch64-linux-gnu/libc.so.6(__libc_start_main+0xe3) [0xfffface22d23] perf(+0x57723) [0xaaaaac8a1723] Segmentation fault This issue is introduced by commit 30a910d7d3e0 ("perf trace: Preallocate the syscall table"), it allocates trace->syscalls.table[] array and the element count is 'trace->sctbl->syscalls.nr_entries'; but on Arm64, the system call number is not continuously used; e.g. the syscall maximum id is 436 but the real entries is only 281. So the table is allocated with 'nr_entries' as the element count, but it accesses the table with the syscall id, which might be out of the bound of the array and cause the segmentation fault. This patch allocates trace->syscalls.table[] with the element count is 'trace->sctbl->syscalls.max_id + 1', this allows any id to access the table without out of the bound. Signed-off-by: Leo Yan Cc: Alexander Shishkin Cc: Daniel Borkmann Cc: Jiri Olsa Cc: Martin KaFai Lau Cc: Namhyung Kim Cc: Song Liu Cc: Yonghong Song Fixes: 30a910d7d3e0 ("perf trace: Preallocate the syscall table") Link: http://lkml.kernel.org/r/20190809104752.27338-1-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 75eb3811e942..d553d06a9aeb 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1492,7 +1492,7 @@ static int trace__read_syscall_info(struct trace *trace, int id) const char *name = syscalltbl__name(trace->sctbl, id); if (trace->syscalls.table == NULL) { - trace->syscalls.table = calloc(trace->sctbl->syscalls.nr_entries, sizeof(*sc)); + trace->syscalls.table = calloc(trace->sctbl->syscalls.max_id + 1, sizeof(*sc)); if (trace->syscalls.table == NULL) return -ENOMEM; }