linux-kernel - [PATCH 5.19 0538/1157] bpf: Fix bpf_xdp

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Message-Id: <20220815180501.185772727@linuxfoundation.org>
Date:   Mon, 15 Aug 2022 19:58:14 +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, Joanne Koong <joannelkoong@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.19 0538/1157] bpf: Fix bpf_xdp_pointer return pointer

From: Joanne Koong <joannelkoong@...il.com>

[ Upstream commit bbd52178e249fe893ef4a9b87cde5b6c473b0a7c ]

For the case where offset + len == size, bpf_xdp_pointer should return a
valid pointer to the addr because that access is permitted. We should
only return NULL in the case where offset + len exceeds size.

Fixes: 3f364222d032 ("net: xdp: introduce bpf_xdp_pointer utility routine")
Signed-off-by: Joanne Koong <joannelkoong@...il.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Martin KaFai Lau <kafai@...com>
Acked-by: Lorenzo Bianconi <lorenzo@...nel.org>
Link: https://lore.kernel.org/bpf/20220722220105.2065466-1-joannelkoong@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/core/filter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 5978984b752f..74f05ed6aff2 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3918,7 +3918,7 @@ static void *bpf_xdp_pointer(struct xdp_buff *xdp, u32 offset, u32 len)
 		offset -= frag_size;
 	}
 out:
-	return offset + len < size ? addr + offset : NULL;
+	return offset + len <= size ? addr + offset : NULL;
 }
 
 BPF_CALL_4(bpf_xdp_load_bytes, struct xdp_buff *, xdp, u32, offset,
-- 
2.35.1