| Message ID | 20180328140302.2594031-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
| Series | tipc: avoid possible string overflow | expand |
From: Arnd Bergmann <arnd@arndb.de> Date: Wed, 28 Mar 2018 16:02:04 +0200 > 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); > > Using snprintf() ensures that the destination is still a nul-terminated > string in all cases. It's still theoretically possible that the string > gets trunctated though, so this patch should be carefully reviewed to > ensure that either truncation is impossible in practice, or that we're > ok with the truncation. > > Fixes: 25b0b9c4e835 ("tipc: handle collisions of 32-bit node address hash values") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Based upon the discussion here, it looks like Jon will fix this in a different way by increasing the destination buffer size.
diff --git a/net/tipc/link.c b/net/tipc/link.c index 1289b4ba404f..c195ba036035 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;
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); Using snprintf() ensures that the destination is still a nul-terminated string in all cases. It's still theoretically possible that the string gets trunctated though, so this patch should be carefully reviewed to ensure that either truncation is impossible in practice, or that we're ok with the truncation. Fixes: 25b0b9c4e835 ("tipc: handle collisions of 32-bit node address hash values") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- net/tipc/link.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 2.9.0