5.4-stable review patch. If anyone has any objections, please let me know.
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From: Phil Sutter phil@nwl.cc
[ Upstream commit 456f010bfaefde84d3390c755eedb1b0a5857c3c ]
User space may unload ip_set.ko while it is itself requesting a set type backend module, leading to a kernel crash. The race condition may be provoked by inserting an mdelay() right after the nfnl_unlock() call.
Fixes: a7b4f989a629 ("netfilter: ipset: IP set core support") Signed-off-by: Phil Sutter phil@nwl.cc Acked-by: Jozsef Kadlecsik kadlec@netfilter.org Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/ipset/ip_set_core.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c index 83fa95ecaad47..1ce19162ebf79 100644 --- a/net/netfilter/ipset/ip_set_core.c +++ b/net/netfilter/ipset/ip_set_core.c @@ -103,14 +103,19 @@ find_set_type(const char *name, u8 family, u8 revision) static bool load_settype(const char *name) { + if (!try_module_get(THIS_MODULE)) + return false; + nfnl_unlock(NFNL_SUBSYS_IPSET); pr_debug("try to load ip_set_%s\n", name); if (request_module("ip_set_%s", name) < 0) { pr_warn("Can't find ip_set type %s\n", name); nfnl_lock(NFNL_SUBSYS_IPSET); + module_put(THIS_MODULE); return false; } nfnl_lock(NFNL_SUBSYS_IPSET); + module_put(THIS_MODULE); return true; }