From 9f19aab47ced012eddef1e2bc96007efc7713b61 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Thu, 5 Jan 2023 00:26:09 -0800 Subject: [PATCH] perf llvm: Fix inadvertent file creation The LLVM template is first echo-ed into command_out and then command_out executed. The echo surrounds the template with double quotes, however, the template itself may contain quotes. This is generally innocuous but in tools/perf/tests/bpf-script-test-prologue.c we see: ... SEC("func=null_lseek file->f_mode offset orig") ... where the first double quote ends the double quote of the echo, then the > redirects output into a file called f_mode. To avoid this inadvertent behavior substitute redirects and similar characters to be ASCII control codes, then substitute the output in the echo back again. Fixes: 5eab5a7ee032acaa ("perf llvm: Display eBPF compiling command in debug output") Signed-off-by: Ian Rogers Cc: Alexander Shishkin Cc: Andrii Nakryiko Cc: bpf@vger.kernel.org Cc: Ingo Molnar Cc: Jiri Olsa Cc: llvm@lists.linux.dev Cc: Mark Rutland Cc: Namhyung Kim Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Peter Zijlstra Cc: Tom Rix Link: https://lore.kernel.org/r/20230105082609.344538-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/llvm-utils.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c index 650ffe3..4e8e243a 100644 --- a/tools/perf/util/llvm-utils.c +++ b/tools/perf/util/llvm-utils.c @@ -531,14 +531,37 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf, pr_debug("llvm compiling command template: %s\n", template); + /* + * Below, substitute control characters for values that can cause the + * echo to misbehave, then substitute the values back. + */ err = -ENOMEM; - if (asprintf(&command_echo, "echo -n \"%s\"", template) < 0) + if (asprintf(&command_echo, "echo -n \a%s\a", template) < 0) goto errout; +#define SWAP_CHAR(a, b) do { if (*p == a) *p = b; } while (0) + for (char *p = command_echo; *p; p++) { + SWAP_CHAR('<', '\001'); + SWAP_CHAR('>', '\002'); + SWAP_CHAR('"', '\003'); + SWAP_CHAR('\'', '\004'); + SWAP_CHAR('|', '\005'); + SWAP_CHAR('&', '\006'); + SWAP_CHAR('\a', '"'); + } err = read_from_pipe(command_echo, (void **) &command_out, NULL); if (err) goto errout; + for (char *p = command_out; *p; p++) { + SWAP_CHAR('\001', '<'); + SWAP_CHAR('\002', '>'); + SWAP_CHAR('\003', '"'); + SWAP_CHAR('\004', '\''); + SWAP_CHAR('\005', '|'); + SWAP_CHAR('\006', '&'); + } +#undef SWAP_CHAR pr_debug("llvm compiling command : %s\n", command_out); err = read_from_pipe(template, &obj_buf, &obj_buf_sz); -- 2.7.4