From: Lorenz Bauer <[email protected]>

[ Upstream commit f9b7ff0d7f7a466a920424246e7ddc2b84c87e52 ]

My earlier patch to reject non-zero arguments to flow dissector attach
broke attaching via bpftool. Instead of 0 it uses -1 for target_fd.
Fix this by passing a zero argument when attaching the flow dissector.

Fixes: 1b514239e859 ("bpf: flow_dissector: Check value of unused flags to 
BPF_PROG_ATTACH")
Reported-by: Jiri Benc <[email protected]>
Signed-off-by: Lorenz Bauer <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Acked-by: Song Liu <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
Signed-off-by: Sasha Levin <[email protected]>
---
 tools/bpf/bpftool/prog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index d393eb8263a60..994506540e564 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -741,7 +741,7 @@ static int parse_attach_detach_args(int argc, char **argv, 
int *progfd,
        }
 
        if (*attach_type == BPF_FLOW_DISSECTOR) {
-               *mapfd = -1;
+               *mapfd = 0;
                return 0;
        }
 
-- 
2.27.0



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