linux-kernel - [PATCH 5.6 063/126] bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval

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Message-Id: <20200526183943.453926113@linuxfoundation.org>
Date:   Tue, 26 May 2020 20:53:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Yonghong Song <yhs@...com>
Subject: [PATCH 5.6 063/126] bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range

From: Daniel Borkmann <daniel@...earbox.net>

commit 47cc0ed574abcbbde0cf143ddb21a0baed1aa2df upstream.

Given bpf_probe_read{,str}() BPF helpers are now only available under
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, we need to add the drop-in
replacements of bpf_probe_read_{kernel,user}_str() to do_refine_retval_range()
as well to avoid hitting the same issue as in 849fa50662fbc ("bpf/verifier:
refine retval R0 state for bpf_get_stack helper").

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Acked-by: John Fastabend <john.fastabend@...il.com>
Acked-by: Yonghong Song <yhs@...com>
Link: https://lore.kernel.org/bpf/20200515101118.6508-3-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/bpf/verifier.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4113,7 +4113,9 @@ static int do_refine_retval_range(struct
 
 	if (ret_type != RET_INTEGER ||
 	    (func_id != BPF_FUNC_get_stack &&
-	     func_id != BPF_FUNC_probe_read_str))
+	     func_id != BPF_FUNC_probe_read_str &&
+	     func_id != BPF_FUNC_probe_read_kernel_str &&
+	     func_id != BPF_FUNC_probe_read_user_str))
 		return 0;
 
 	/* Error case where ret is in interval [S32MIN, -1]. */