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Commit 5d32f3e9 authored by Ian Rogers's avatar Ian Rogers Committed by Greg Kroah-Hartman
Browse files

perf llvm: Fix inadvertent file creation 



[ Upstream commit 9f19aab47ced012eddef1e2bc96007efc7713b61 ]

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: 5eab5a7e ("perf llvm: Display eBPF compiling command in debug output")
Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: llvm@lists.linux.dev
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20230105082609.344538-1-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent ce43565a

tools/perf/util/llvm-utils.c

+24 −1
Original line number Diff line number Diff line
@@ -523,14 +523,37 @@ 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);