[PATCH 5.10 09/43] bpf: Support PTR_TO_MEM{,_OR_NULL} register spilling

[Greg Kroah-Hartman]

From: Gilad Reti <gilad.reti@xxxxxxxxx>

commit 744ea4e3885eccb6d332a06fae9eb7420a622c0f upstream.

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@xxxxxx>
Signed-off-by: Gilad Reti <gilad.reti@xxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: KP Singh <kpsingh@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210113053810.13518-1-gilad.reti@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2214,6 +2214,8 @@ static bool is_spillable_regtype(enum bp
 	case PTR_TO_RDWR_BUF:
 	case PTR_TO_RDWR_BUF_OR_NULL:
 	case PTR_TO_PERCPU_BTF_ID:
+	case PTR_TO_MEM:
+	case PTR_TO_MEM_OR_NULL:
 		return true;
 	default:
 		return false;