Commit defac894 authored by Christoph Werle's avatar Christoph Werle Committed by Andrii Nakryiko
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bpftool: Fix control flow graph segfault during edge creation 



If the last instruction of a control flow graph building block is a
BPF_CALL, an incorrect edge with e->dst set to NULL is created and
results in a segfault during graph output.

Ensure that BPF_CALL as last instruction of a building block is handled
correctly and only generates a single edge unlike actual BPF_JUMP*
instructions.

Signed-off-by: default avatarChristoph Werle <christoph.werle@longjmp.de>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Tested-by: default avatarQuentin Monnet <qmo@kernel.org>
Reviewed-by: default avatarQuentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20250108220937.1470029-1-christoph.werle@longjmp.de
parent a43796b5

tools/bpf/bpftool/cfg.c

+1 −0
Original line number Diff line number Diff line
@@ -302,6 +302,7 @@ static bool func_add_bb_edges(struct func_node *func) 


		insn = bb->tail;

		if (!is_jmp_insn(insn->code) ||

		    BPF_OP(insn->code) == BPF_CALL ||

		    BPF_OP(insn->code) == BPF_EXIT) {

			e->dst = bb_next(bb);

			e->flags |= EDGE_FLAG_FALLTHROUGH;