| From b2b4c03caf1fc890b25f1febc264f523cb23d71d Mon Sep 17 00:00:00 2001 |
| From: Jiri Olsa <jolsa@kernel.org> |
| Date: Fri, 18 Jan 2019 13:58:17 +0100 |
| Subject: bpftool: Fix prog dump by tag |
| |
| [ Upstream commit 752bcf80f5549c9901b2e8bc77b2138de55b1026 ] |
| |
| Lance reported an issue with bpftool not being able to |
| dump program if there are more programs loaded and you |
| want to dump any but the first program, like: |
| |
| # bpftool prog |
| 28: kprobe name trace_req_start tag 1dfc28ba8b3dd597 gpl |
| loaded_at 2019-01-18T17:02:40+1100 uid 0 |
| xlated 112B jited 109B memlock 4096B map_ids 13 |
| 29: kprobe name trace_req_compl tag 5b6a5ecc6030a683 gpl |
| loaded_at 2019-01-18T17:02:40+1100 uid 0 |
| xlated 928B jited 575B memlock 4096B map_ids 13,14 |
| # bpftool prog dum jited tag 1dfc28ba8b3dd597 |
| 0: push %rbp |
| 1: mov %rsp,%rbp |
| ... |
| |
| # bpftool prog dum jited tag 5b6a5ecc6030a683 |
| Error: can't get prog info (29): Bad address |
| |
| The problem is in the prog_fd_by_tag function not cleaning |
| the struct bpf_prog_info before another request, so the |
| previous program length is still in there and kernel assumes |
| it needs to dump the program, which fails because there's no |
| user pointer set. |
| |
| Moving the struct bpf_prog_info declaration into the loop, |
| so it gets cleaned before each query. |
| |
| Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool") |
| Reported-by: Lance Digby <ldigby@redhat.com> |
| Signed-off-by: Jiri Olsa <jolsa@kernel.org> |
| Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> |
| Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com> |
| Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| tools/bpf/bpftool/prog.c | 5 +++-- |
| 1 file changed, 3 insertions(+), 2 deletions(-) |
| |
| diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c |
| index 0de024a6cc2b..bbba0d61570f 100644 |
| --- a/tools/bpf/bpftool/prog.c |
| +++ b/tools/bpf/bpftool/prog.c |
| @@ -109,13 +109,14 @@ static void print_boot_time(__u64 nsecs, char *buf, unsigned int size) |
| |
| static int prog_fd_by_tag(unsigned char *tag) |
| { |
| - struct bpf_prog_info info = {}; |
| - __u32 len = sizeof(info); |
| unsigned int id = 0; |
| int err; |
| int fd; |
| |
| while (true) { |
| + struct bpf_prog_info info = {}; |
| + __u32 len = sizeof(info); |
| + |
| err = bpf_prog_get_next_id(id, &id); |
| if (err) { |
| p_err("%s", strerror(errno)); |
| -- |
| 2.19.1 |
| |