[PATCH] tipc: Avoid copying bytes beyond the supplied data

From: Chris Packham
Date: Wed May 01 2019 - 23:10:34 EST

TLV_SET is called with a data pointer and a len parameter that tells us
how many bytes are pointed to by data. When invoking memcpy() we need
to careful to only copy len bytes.

Previously we would copy TLV_LENGTH(len) bytes which would copy an extra
4 bytes past the end of the data pointer which newer GCC versions
complain about.

In file included from test.c:17:
In function 'TLV_SET',
inlined from 'test' at test.c:186:5:
warning: 'memcpy' forming offset [33, 36] is out of the bounds [0, 32]
of object 'bearer_name' with type 'char[32]' [-Warray-bounds]
memcpy(TLV_DATA(tlv_ptr), data, tlv_len);
test.c: In function 'test':
test.c::161:10: note:
'bearer_name' declared here
char bearer_name[TIPC_MAX_BEARER_NAME];

Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
include/uapi/linux/tipc_config.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/tipc_config.h b/include/uapi/linux/tipc_config.h
index 4b2c93b1934c..f65c5b80ed33 100644
--- a/include/uapi/linux/tipc_config.h
+++ b/include/uapi/linux/tipc_config.h
@@ -308,7 +308,7 @@ static inline int TLV_SET(void *tlv, __u16 type, void *data, __u16 len)
tlv_ptr->tlv_type = htons(type);
tlv_ptr->tlv_len = htons(tlv_len);
if (len && data)
- memcpy(TLV_DATA(tlv_ptr), data, tlv_len);
+ memcpy(TLV_DATA(tlv_ptr), data, len);
return TLV_SPACE(len);