From 7494cfa6d36d1556f17baa012dd93833620783db Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Thu, 29 Mar 2018 23:20:45 +0200 Subject: tipc: avoid possible string overflow gcc points out that the combined length of the fixed-length inputs to l->name is larger than the destination buffer size: net/tipc/link.c: In function 'tipc_link_create': net/tipc/link.c:465:26: error: '%s' directive writing up to 32 bytes into a region of size between 26 and 58 [-Werror=format-overflow=] sprintf(l->name, "%s:%s-%s:unknown", self_str, if_name, peer_str); net/tipc/link.c:465:2: note: 'sprintf' output 11 or more bytes (assuming 75) into a destination of size 60 sprintf(l->name, "%s:%s-%s:unknown", self_str, if_name, peer_str); A detailed analysis reveals that the theoretical maximum length of a link name is: max self_str + 1 + max if_name + 1 + max peer_str + 1 + max if_name = 16 + 1 + 15 + 1 + 16 + 1 + 15 = 65 Since we also need space for a trailing zero we now set MAX_LINK_NAME to 68. Just to be on the safe side we also replace the sprintf() call with snprintf(). Fixes: 25b0b9c4e835 ("tipc: handle collisions of 32-bit node address hash values") Reported-by: Arnd Bergmann Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/link.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/tipc') diff --git a/net/tipc/link.c b/net/tipc/link.c index 8f2a9496439b..695acb783969 100644 --- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -462,7 +462,8 @@ bool tipc_link_create(struct net *net, char *if_name, int bearer_id, sprintf(peer_str, "%x", peer); } /* Peer i/f name will be completed by reset/activate message */ - sprintf(l->name, "%s:%s-%s:unknown", self_str, if_name, peer_str); + snprintf(l->name, sizeof(l->name), "%s:%s-%s:unknown", + self_str, if_name, peer_str); strcpy(l->if_name, if_name); l->addr = peer; -- cgit v1.2.3