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bpftool: Fix control flow graph segfault during edge creation

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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: Christoph Werle <christoph.werle@longjmp.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Quentin Monnet <qmo@kernel.org>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20250108220937.1470029-1-christoph.werle@longjmp.de
This commit is contained in:
Christoph Werle
2025-01-08 23:09:37 +01:00
committed by Andrii Nakryiko
parent a43796b520
commit defac894af
1 changed files with 1 additions and 0 deletions
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1
tools/bpf/bpftool/cfg.c
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@@ -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;