Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] netfilter: fix stringop-overflow warning with UBSAN | Date | Mon, 31 Jul 2017 12:09:03 +0200 |
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Using gcc-7 with UBSAN enabled, we get this false-positive warning:
net/netfilter/ipset/ip_set_core.c: In function 'ip_set_sockfn_get': net/netfilter/ipset/ip_set_core.c:1998:3: error: 'strncpy' writing 32 bytes into a region of size 2 overflows the destination [-Werror=stringop-overflow=] strncpy(req_get->set.name, set ? set->name : "", ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ sizeof(req_get->set.name)); ~~~~~~~~~~~~~~~~~~~~~~~~~~
This seems completely bogus, and I could not find a nice workaround. To work around it in a less elegant way, I change the ?: operator into an if()/else() construct.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- net/netfilter/ipset/ip_set_core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index e495b5e484b1..d7ebb021003b 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -1995,8 +1995,12 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len) } nfnl_lock(NFNL_SUBSYS_IPSET); set = ip_set(inst, req_get->set.index); - strncpy(req_get->set.name, set ? set->name : "", - IPSET_MAXNAMELEN); + if (set) + strncpy(req_get->set.name, set->name, + sizeof(req_get->set.name)); + else + memset(req_get->set.name, '\0', + sizeof(req_get->set.name)); nfnl_unlock(NFNL_SUBSYS_IPSET); goto copy; } -- 2.9.0
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