bpftool: fix potential NULL pointer dereferencing in prog_dump()

[ Upstream commit ef3ba8c258ee368a5343fa9329df85b4bcb9e8b5 ]

A NULL pointer dereference could occur if ksyms
is not properly checked before usage in the prog_dump() function.

Fixes: b053b439 ("bpf: libbpf: bpftool: Print bpf_line_info during prog dump")
Signed-off-by: Amir Mohammadi <amiremohamadi@yahoo.com>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20241121083413.7214-1-amiremohamadi@yahoo.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>