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authorVasily Averin <vvs@virtuozzo.com>2021-02-27 11:27:45 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2021-02-28 00:25:16 +0100
commit8e24edddad152b998b37a7f583175137ed2e04a5 (patch)
treec981518641a9b59f92ffc833bf81937137f4e980
parentc2c16ccba2f55d527dd145a5d8c038694b3b343f (diff)
netfilter: x_tables: gpf inside xt_find_revision()
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>
-rw-r--r--net/netfilter/x_tables.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index acce622582e3..bce6ca203d46 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -330,6 +330,7 @@ static int match_revfn(u8 af, const char *name, u8 revision, int *bestp)
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)
@@ -338,6 +339,7 @@ static int match_revfn(u8 af, const char *name, u8 revision, int *bestp)
have_rev = 1;
}
}
+ mutex_unlock(&xt[af].mutex);
if (af != NFPROTO_UNSPEC && !have_rev)
return match_revfn(NFPROTO_UNSPEC, name, revision, bestp);
@@ -350,6 +352,7 @@ static int target_revfn(u8 af, const char *name, u8 revision, int *bestp)
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)
@@ -358,6 +361,7 @@ static int target_revfn(u8 af, const char *name, u8 revision, int *bestp)
have_rev = 1;
}
}
+ mutex_unlock(&xt[af].mutex);
if (af != NFPROTO_UNSPEC && !have_rev)
return target_revfn(NFPROTO_UNSPEC, name, revision, bestp);
@@ -371,12 +375,10 @@ int xt_find_revision(u8 af, const char *name, u8 revision, int target,
{
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) {