From: Greg Kroah-Hartman gregkh@linuxfoundation.org
From: Maciej Fijalkowski maciej.fijalkowski@intel.com
commit 2b2aedabc44e9660f90ccf7ba1ca2706d75f411f upstream.
xsk_lookup_bpf_maps, based on prog_fd, looks whether current prog has a reference to XSKMAP. BPF prog can include insns that work on various BPF maps and this is covered by iterating through map_ids.
The bpf_map_info that is passed to bpf_obj_get_info_by_fd for filling needs to be cleared at each iteration, so that it doesn't contain any outdated fields and that is currently missing in the function of interest.
To fix that, zero-init map_info via memset before each bpf_obj_get_info_by_fd call.
Also, since the area of this code is touched, in general strcmp is considered harmful, so let's convert it to strncmp and provide the size of the array name for current map_info.
While at it, do s/continue/break/ once we have found the xsks_map to terminate the search.
Fixes: 5750902a6e9b ("libbpf: proper XSKMAP cleanup") Signed-off-by: Maciej Fijalkowski maciej.fijalkowski@intel.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Björn Töpel bjorn.topel@intel.com Link: https://lore.kernel.org/bpf/20210303185636.18070-4-maciej.fijalkowski@intel.... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/lib/bpf/xsk.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -535,15 +535,16 @@ static int xsk_lookup_bpf_maps(struct xs if (fd < 0) continue;
+ memset(&map_info, 0, map_len); err = bpf_obj_get_info_by_fd(fd, &map_info, &map_len); if (err) { close(fd); continue; }
- if (!strcmp(map_info.name, "xsks_map")) { + if (!strncmp(map_info.name, "xsks_map", sizeof(map_info.name))) { ctx->xsks_map_fd = fd; - continue; + break; }
close(fd);