bpf: Fix check_reg_type for PTR_TO_BTF_ID

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The current code does type matching for the case where reg->type is
PTR_TO_BTF_ID or has the PTR_TRUSTED flag. However, this only needs to
occur for non-MEM_ALLOC and non-MEM_PERCPU cases, but will include both
as per the current code.

The MEM_ALLOC case with or without PTR_TRUSTED needs to be handled
specially by the code for type_is_alloc case, while MEM_PERCPU case must
be ignored. Hence, to restore correct behavior and for clarity,
explicitly list out the handled PTR_TO_BTF_ID types which should be
handled for each case using a switch statement.

Helpers currently only take:
	PTR_TO_BTF_ID
	PTR_TO_BTF_ID | PTR_TRUSTED
	PTR_TO_BTF_ID | MEM_RCU
	PTR_TO_BTF_ID | MEM_ALLOC
	PTR_TO_BTF_ID | MEM_PERCPU
	PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED

This fix was also described (for the MEM_ALLOC case) in [0].

  [0]: https://lore.kernel.org/bpf/20221121160657.h6z7xuvedybp5y7s@apollo

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230221200646.2500777-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

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Kumar Kartikeya Dwivedi 2023-02-21 21:06:44 +01:00 • committed by Alexei Starovoitov

parent 521d3c0a17

commit da03e43a8c

1 changed files with 20 additions and 3 deletions

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kernel/bpf/verifier.c

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