From: Greg Kroah-Hartman gregkh@linuxfoundation.org
From: Vasily Averin vvs@virtuozzo.com
commit 8e24edddad152b998b37a7f583175137ed2e04a5 upstream.
nested target/match_revfn() calls work with xt[NFPROTO_UNSPEC] lists without taking xt[NFPROTO_UNSPEC].mutex. This can race with module unload and cause host to crash:
general protection fault: 0000 [#1] Modules linked in: ... [last unloaded: xt_cluster] CPU: 0 PID: 542455 Comm: iptables RIP: 0010:[<ffffffff8ffbd518>] [<ffffffff8ffbd518>] strcmp+0x18/0x40 RDX: 0000000000000003 RSI: ffff9a5a5d9abe10 RDI: dead000000000111 R13: ffff9a5a5d9abe10 R14: ffff9a5a5d9abd8c R15: dead000000000100 (VvS: %R15 -- &xt_match, %RDI -- &xt_match.name, xt_cluster unregister match in xt[NFPROTO_UNSPEC].match list) Call Trace: [<ffffffff902ccf44>] match_revfn+0x54/0xc0 [<ffffffff902ccf9f>] match_revfn+0xaf/0xc0 [<ffffffff902cd01e>] xt_find_revision+0x6e/0xf0 [<ffffffffc05a5be0>] do_ipt_get_ctl+0x100/0x420 [ip_tables] [<ffffffff902cc6bf>] nf_getsockopt+0x4f/0x70 [<ffffffff902dd99e>] ip_getsockopt+0xde/0x100 [<ffffffff903039b5>] raw_getsockopt+0x25/0x50 [<ffffffff9026c5da>] sock_common_getsockopt+0x1a/0x20 [<ffffffff9026b89d>] SyS_getsockopt+0x7d/0xf0 [<ffffffff903cbf92>] system_call_fastpath+0x25/0x2a
Fixes: 656caff20e1 ("netfilter 04/09: x_tables: fix match/target revision lookup") Signed-off-by: Vasily Averin vvs@virtuozzo.com Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/x_tables.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -271,6 +271,7 @@ static int match_revfn(u8 af, const char const struct xt_match *m; int have_rev = 0;
+ mutex_lock(&xt[af].mutex); list_for_each_entry(m, &xt[af].match, list) { if (strcmp(m->name, name) == 0) { if (m->revision > *bestp) @@ -279,6 +280,7 @@ static int match_revfn(u8 af, const char have_rev = 1; } } + mutex_unlock(&xt[af].mutex);
if (af != NFPROTO_UNSPEC && !have_rev) return match_revfn(NFPROTO_UNSPEC, name, revision, bestp); @@ -291,6 +293,7 @@ static int target_revfn(u8 af, const cha const struct xt_target *t; int have_rev = 0;
+ mutex_lock(&xt[af].mutex); list_for_each_entry(t, &xt[af].target, list) { if (strcmp(t->name, name) == 0) { if (t->revision > *bestp) @@ -299,6 +302,7 @@ static int target_revfn(u8 af, const cha have_rev = 1; } } + mutex_unlock(&xt[af].mutex);
if (af != NFPROTO_UNSPEC && !have_rev) return target_revfn(NFPROTO_UNSPEC, name, revision, bestp); @@ -312,12 +316,10 @@ int xt_find_revision(u8 af, const char * { int have_rev, best = -1;
- mutex_lock(&xt[af].mutex); if (target == 1) have_rev = target_revfn(af, name, revision, &best); else have_rev = match_revfn(af, name, revision, &best); - mutex_unlock(&xt[af].mutex);
/* Nothing at all? Return 0 to try loading module. */ if (best == -1) {