On 01/18/2019 01:58 PM, Jiri Olsa wrote: > 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. > > Reported-by: Lance Digby <ldi...@redhat.com> > Signed-off-by: Jiri Olsa <jo...@kernel.org>
Applied to bpf and added Fixes tags, thanks!
