From: Gilad Reti <gilad.reti@gmail.com>
Date: Wed, 13 Jan 2021 07:38:07 +0200
Subject: bpf: Support PTR_TO_MEM{,_OR_NULL} register spilling
Patch-mainline: v5.11 or v5.11-rc5 (next release)
Git-commit: 744ea4e3885eccb6d332a06fae9eb7420a622c0f
References: bsc#1177028

Add support for pointer to mem register spilling, to allow the verifier
to track pointers to valid memory addresses. Such pointers are returned
for example by a successful call of the bpf_ringbuf_reserve helper.

The patch was partially contributed by CyberArk Software, Inc.

Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Suggested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Gilad Reti <gilad.reti@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210113053810.13518-1-gilad.reti@gmail.com
Acked-by: Gary Lin <glin@suse.com>

NOTE from Gary:
  Ignored "case PTR_TO_PERCPU_BTF_ID" in the original patch

---
 kernel/bpf/verifier.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2181,6 +2181,8 @@ static bool is_spillable_regtype(enum bp
 	case PTR_TO_RDONLY_BUF_OR_NULL:
 	case PTR_TO_RDWR_BUF:
 	case PTR_TO_RDWR_BUF_OR_NULL:
+	case PTR_TO_MEM:
+	case PTR_TO_MEM_OR_NULL:
 		return true;
 	default:
 		return false;