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flow_dissector: Fix out-of-bounds warning in __skb_flow_bpf_to_target()
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[ Upstream commit 1e3d976 ]

Fix the following out-of-bounds warning:

net/core/flow_dissector.c:835:3: warning: 'memcpy' offset [33, 48] from the object at 'flow_keys' is out of the bounds of referenced subobject 'ipv6_src' with type '__u32[4]' {aka 'unsigned int[4]'} at offset 16 [-Warray-bounds]

The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy().  So, the compiler legitimately complains about it. As these
are just a couple of members, fix this by copying each one of them in
separate calls to memcpy().

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: KSPP/linux#109
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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GustavoARSilva authored and gregkh committed May 19, 2021
1 parent d571662 commit 245f5ab
Showing 1 changed file with 4 additions and 2 deletions.
6 changes: 4 additions & 2 deletions net/core/flow_dissector.c
Expand Up @@ -822,8 +822,10 @@ static void __skb_flow_bpf_to_target(const struct bpf_flow_keys *flow_keys,
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IPV6_ADDRS,
target_container);
memcpy(&key_addrs->v6addrs, &flow_keys->ipv6_src,
sizeof(key_addrs->v6addrs));
memcpy(&key_addrs->v6addrs.src, &flow_keys->ipv6_src,
sizeof(key_addrs->v6addrs.src));
memcpy(&key_addrs->v6addrs.dst, &flow_keys->ipv6_dst,
sizeof(key_addrs->v6addrs.dst));
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
}

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