From b5dad703517e43dd47285a8a6dcffc024db88bdf Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 30 Apr 2020 23:30:48 +0200 Subject: [PATCH] netfilter: conntrack: avoid gcc-10 zero-length-bounds warning [ Upstream commit 2c407aca64977ede9b9f35158e919773cae2082f ] gcc-10 warns around a suspicious access to an empty struct member: net/netfilter/nf_conntrack_core.c: In function '__nf_conntrack_alloc': net/netfilter/nf_conntrack_core.c:1522:9: warning: array subscript 0 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[0]'} [-Wzero-length-bounds] 1522 | memset(&ct->__nfct_init_offset[0], 0, | ^~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from net/netfilter/nf_conntrack_core.c:37: include/net/netfilter/nf_conntrack.h:90:5: note: while referencing '__nfct_init_offset' 90 | u8 __nfct_init_offset[0]; | ^~~~~~~~~~~~~~~~~~ The code is correct but a bit unusual. Rework it slightly in a way that does not trigger the warning, using an empty struct instead of an empty array. There are probably more elegant ways to do this, but this is the smallest change. Fixes: c41884ce0562 ("netfilter: conntrack: avoid zeroing timer") Signed-off-by: Arnd Bergmann Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- include/net/netfilter/nf_conntrack.h | 2 +- net/netfilter/nf_conntrack_core.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index 636e9e11bd5f..e3f73fd1d53a 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -98,7 +98,7 @@ struct nf_conn { possible_net_t ct_net; /* all members below initialized via memset */ - u8 __nfct_init_offset[0]; + struct { } __nfct_init_offset; /* If we were expected by an expectation, this will be it */ struct nf_conn *master; diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index de0aad12b91d..e58516274e86 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -898,9 +898,9 @@ __nf_conntrack_alloc(struct net *net, /* Don't set timer yet: wait for confirmation */ setup_timer(&ct->timeout, death_by_timeout, (unsigned long)ct); write_pnet(&ct->ct_net, net); - memset(&ct->__nfct_init_offset[0], 0, + memset(&ct->__nfct_init_offset, 0, offsetof(struct nf_conn, proto) - - offsetof(struct nf_conn, __nfct_init_offset[0])); + offsetof(struct nf_conn, __nfct_init_offset)); if (zone && nf_ct_zone_add(ct, GFP_ATOMIC, zone) < 0) goto out_free;