[PATCH 4.9 12/12] bpf: Enlarge offset check value to INT_MAX in bpf_skb_{load,store}_bytes

[Greg Kroah-Hartman]

From: Liu Jian <liujian56@xxxxxxxxxx>

commit 45969b4152c1752089351cd6836a42a566d49bcf upstream.

The data length of skb frags + frag_list may be greater than 0xffff, and
skb_header_pointer can not handle negative offset. So, here INT_MAX is used
to check the validity of offset. 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@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
Link: https://lore.kernel.org/bpf/20220416105801.88708-2-liujian56@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/filter.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1388,7 +1388,7 @@ BPF_CALL_5(bpf_skb_store_bytes, struct s
 
 	if (unlikely(flags & ~(BPF_F_RECOMPUTE_CSUM | BPF_F_INVALIDATE_HASH)))
 		return -EINVAL;
-	if (unlikely(offset > 0xffff))
+	if (unlikely(offset > INT_MAX))
 		return -EFAULT;
 	if (unlikely(bpf_try_make_writable(skb, offset + len)))
 		return -EFAULT;
@@ -1423,7 +1423,7 @@ BPF_CALL_4(bpf_skb_load_bytes, const str
 {
 	void *ptr;
 
-	if (unlikely(offset > 0xffff))
+	if (unlikely(offset > INT_MAX))
 		goto err_clear;
 
 	ptr = skb_header_pointer(skb, offset, len, to);