selftests/bpf: Check the linked regs cap for the compared register

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linked_regs_too_many_regs checks that collect_linked_regs() ties at most
LINKED_REGS_MAX registers for a single jump. Compare r5 instead of r0,
so that the register the jump compares is itself the member that does
not fit, and check that it comes out of the jump unlinked.

W/o the previous patch env->{false,true}_reg{1,2} bring r5's id back and
insn 7 is logged as "R5=scalar(id=1,...)".

Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260904083325.2083493-4-eddyz87@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

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Eduard Zingerman 2026-09-04 01:33:21 -07:00 • committed by Kumar Kartikeya Dwivedi

parent 73a98f9681

commit bc412b3fb1

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tools/testing/selftests/bpf/progs/verifier_scalar_ids.c

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