4.19-stable review patch. If anyone has any objections, please let me know.
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From: Zhengchao Shao shaozhengchao@huawei.com
[ Upstream commit 234ec0b6034b16869d45128b8cd2dc6ffe596f04 ]
I analyze the potential sleeping issue of the following processes: Thread A Thread B ... netlink_create //ref = 1 do_mq_notify ... sock = netlink_getsockbyfilp ... //ref = 2 info->notify_sock = sock; ... ... netlink_sendmsg ... skb = netlink_alloc_large_skb //skb->head is vmalloced ... netlink_unicast ... sk = netlink_getsockbyportid //ref = 3 ... netlink_sendskb ... __netlink_sendskb ... skb_queue_tail //put skb to sk_receive_queue ... sock_put //ref = 2 ... ... ... netlink_release ... deferred_put_nlk_sk //ref = 1 mqueue_flush_file spin_lock remove_notification netlink_sendskb sock_put //ref = 0 sk_free ... __sk_destruct netlink_sock_destruct skb_queue_purge //get skb from sk_receive_queue ... __skb_queue_purge_reason kfree_skb_reason __kfree_skb ... skb_release_all skb_release_head_state netlink_skb_destructor vfree(skb->head) //sleeping while holding spinlock
In netlink_sendmsg, if the memory pointed to by skb->head is allocated by vmalloc, and is put to sk_receive_queue queue, also the skb is not freed. When the mqueue executes flush, the sleeping bug will occur. Use vfree_atomic instead of vfree in netlink_skb_destructor to solve the issue.
Fixes: c05cdb1b864f ("netlink: allow large data transfers from user-space") Signed-off-by: Zhengchao Shao shaozhengchao@huawei.com Link: https://lore.kernel.org/r/20240122011807.2110357-1-shaozhengchao@huawei.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/netlink/af_netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index e91489b3274c..72936d154c96 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -374,7 +374,7 @@ static void netlink_skb_destructor(struct sk_buff *skb) if (is_vmalloc_addr(skb->head)) { if (!skb->cloned || !atomic_dec_return(&(skb_shinfo(skb)->dataref))) - vfree(skb->head); + vfree_atomic(skb->head);
skb->head = NULL; }