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bpf: force strict alignment checks for stack pointers
Force strict alignment checks for stack pointers because the tracking of
stack spills relies on it; unaligned stack accesses can lead to corruption
of spilled registers, which is exploitable.
Fixes: f1174f77b5
("bpf/verifier: rework value tracking")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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@ -1059,6 +1059,11 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
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break;
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case PTR_TO_STACK:
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pointer_desc = "stack ";
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/* The stack spill tracking logic in check_stack_write()
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* and check_stack_read() relies on stack accesses being
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* aligned.
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*/
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strict = true;
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break;
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default:
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break;
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