netdev - [PATCH bpf v2 1/2] net: Enlarge offset check value from 0xffff to INT_MAX in bpf_skb_load

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Date:   Wed, 13 Apr 2022 14:21:30 +0800
From:   Liu Jian <liujian56@...wei.com>
To:     <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
        <kafai@...com>, <songliubraving@...com>, <yhs@...com>,
        <john.fastabend@...il.com>, <kpsingh@...nel.org>,
        <davem@...emloft.net>, <kuba@...nel.org>, <sdf@...gle.com>,
        <netdev@...r.kernel.org>, <bpf@...r.kernel.org>
CC:     <liujian56@...wei.com>
Subject: [PATCH bpf v2 1/2] net: Enlarge offset check value from 0xffff to INT_MAX in bpf_skb_load_bytes

The data length of skb frags + frag_list may be greater than 0xffff,
and skb_header_pointer can not handle negative offset and negative len.
So here INT_MAX is used to check the validity of offset and len.
Add the same change to the related function skb_store_bytes.

Fixes: 05c74e5e53f6 ("bpf: add bpf_skb_load_bytes helper")
Signed-off-by: Liu Jian <liujian56@...wei.com>
Acked-by: Song Liu <songliubraving@...com>
---
v1->v2: change nothing, only add Acked-by tag
 net/core/filter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 64470a727ef7..1571b6bc51ea 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1687,7 +1687,7 @@ BPF_CALL_5(bpf_skb_store_bytes, struct sk_buff *, skb, u32, offset,
 
 	if (unlikely(flags & ~(BPF_F_RECOMPUTE_CSUM | BPF_F_INVALIDATE_HASH)))
 		return -EINVAL;
-	if (unlikely(offset > 0xffff))
+	if (unlikely(offset > INT_MAX || len > INT_MAX))
 		return -EFAULT;
 	if (unlikely(bpf_try_make_writable(skb, offset + len)))
 		return -EFAULT;
@@ -1722,7 +1722,7 @@ BPF_CALL_4(bpf_skb_load_bytes, const struct sk_buff *, skb, u32, offset,
 {
 	void *ptr;
 
-	if (unlikely(offset > 0xffff))
+	if (unlikely(offset > INT_MAX || len > INT_MAX))
 		goto err_clear;
 
 	ptr = skb_header_pointer(skb, offset, len, to);
-- 
2.17.1