bpf: Limit caller's stack depth 256 for subprogs with tailcalls

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Protect against potential stack overflow that might happen when bpf2bpf
calls get combined with tailcalls. Limit the caller's stack depth for
such case down to 256 so that the worst case scenario would result in 8k
stack size (32 which is tailcall limit * 256 = 8k).

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Maciej Fijalkowski 2020-09-16 23:10:07 +02:00 • committed by Alexei Starovoitov

parent cf71b174d3

commit 7f6e4312e1

2 changed files with 30 additions and 0 deletions

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1

include/linux/bpf_verifier.h

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29

kernel/bpf/verifier.c

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