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([39.156.73.10]) by newxmesmtplogicsvrsza15-1.qq.com (NewEsmtp) with SMTP id 2B13D4E0; Thu, 05 Dec 2024 19:10:49 +0800 X-QQ-mid: xmsmtpt1733397049ts0bwkeoh Message-ID: X-QQ-XMAILINFO: M/NR0wiIuy70mzeAOdqisJZc4qoxlPnWZNFd2f5QhD8shWaBqSNIuRhBFcf9n1 DFvucvxiS3L1heCnwq/eqHSIs3+kKMrr58fpj/Pcmqhig/2/S21JIbSfguzD3jAqYzWDoRPcCB02 c79cobqbFI7aJy9aQbynAgz9BsxDGeAn992BujD9X9VSotZl7DPB2B7KyY0qp3avUd2nEUHcgBDt FD4iytXR3kO9pL9wgMR44RpuUyGQpccYTcKK7R99UkuqmqMN1vDY6VnJZNzlWzU8vQDYmuWqjVQw 7XRDjE8WzWFlmnVWWNWv436q+z0c2jFbOIS9gH7iHexXYX8IDzWS/SYZXUWJp3/PdtR/Iw1B9/QL 1IVkEs4bdlpddwwjocE7I3Vh2ckG9WVyouimCVIiiPVek9MpvxL6QUqVXRS6D9VeXp3k6GR3CzlU zyI3zF2bWJ1dLaYKTmX87lsyINjTS/hcs/+ih3iJ7pR7N2WwxI71hMGtftAKvIezFQEpyKPrpy3I E8VPGvRksNWOpwVNvXUb1Temc0vHGPUe6f58jLHvxB86bDp826ufOwaHRPUJTMpcT9i0hVjEP/0x vObvTmQGvboOZ9Hy2zEz2KaligV9TGW/s69y186xj6zUZXtTdp/mR+/CXUTbQdhuVwFOQir82RGp jnKO09icfNXWsqDdmbEf7Iis0o2HD0MUcGiPMndsziPFh9O/qFI2HTiAMsOZLkWcDN3nFIuW0vqe SI3cxe8nD/gjoc0PrlLnxsucUc4PO8dJ6xF/zig5/0amy9oGxs8+4zBJyyp040YC6nZqXi74znKl WNyTaZr3Ezap+PZqbdHDUaiP3X05rR7ZAw1yUnytUalgM920Th94qKsBYq3hawS5eO+AXmYNGJWZ dDk34PWR9MtfmSeG5ULW/DDd4ZYSvtLP8m4uaAWCnJ1cQ89FL1v9Lyk1auK22DXsrBbZPjO/yR4z x/0I+mZyLBJyvoj0rRbSaEnFudpeFe X-QQ-XMRINFO: MPJ6Tf5t3I/ycC2BItcBVIA= From: Rong Tao To: qmo@kernel.org, ast@kernel.org, daniel@iogearbox.net, rongtao@cestc.cn Cc: Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf@vger.kernel.org (open list:BPF [TOOLING] (bpftool)), linux-kernel@vger.kernel.org (open list) Subject: [PATCH bpf-next v2] bpftool: Fix gen object segfault Date: Thu, 5 Dec 2024 19:10:35 +0800 X-OQ-MSGID: <20241205111036.278172-1-rtoax@foxmail.com> X-Mailer: git-send-email 2.47.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rong Tao If the input file and output file are the same, the input file is cleared due to opening, resulting in a NULL pointer access by libbpf. $ bpftool gen object prog.o prog.o libbpf: failed to get ELF header for prog.o: invalid `Elf' handle Segmentation fault (gdb) bt #0 0x0000000000450285 in linker_append_elf_syms (linker=3D0x4feda0, ob= j=3D0x7fffffffe100) at linker.c:1296 #1 bpf_linker__add_file (linker=3D0x4feda0, filename=3D= , opts=3D) at linker.c:453 #2 0x000000000040c235 in do_object () #3 0x00000000004021d7 in main () (gdb) frame 0 #0 0x0000000000450285 in linker_append_elf_syms (linker=3D0x4feda0, ob= j=3D0x7fffffffe100) at linker.c:1296 1296 Elf64_Sym *sym =3D symtab->data->d_buf; Signed-off-by: Rong Tao --- v1: https://lore.kernel.org/lkml/tencent_410B8166C55CD2AB64BDEA8E9220461918= 0A@qq.com/ --- tools/bpf/bpftool/gen.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 5a4d3240689e..506d205138db 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -1879,6 +1879,8 @@ static int do_object(int argc, char **argv) struct bpf_linker *linker; const char *output_file, *file; int err =3D 0; + int argc_cpy =3D argc; + char **argv_cpy =3D argv; =20 if (!REQ_ARGS(2)) { usage(); @@ -1887,6 +1889,14 @@ static int do_object(int argc, char **argv) =20 output_file =3D GET_ARG(); =20 + /* Ensure we don't overwrite any input file */ + while (argc_cpy--) { + if (!strcmp(output_file, *argv_cpy++)) { + p_err("Input and output files cannot be the same"); + goto out; + } + } + linker =3D bpf_linker__new(output_file, NULL); if (!linker) { p_err("failed to create BPF linker instance"); --=20 2.47.1