From 1ccb1fa41f4c5f4972c83aa0dfbc70f0b9a38bd6 Mon Sep 17 00:00:00 2001 From: Wang Hai Date: Wed, 18 Aug 2021 20:48:45 +0800 Subject: [PATCH] VMCI: fix NULL pointer dereference when unmapping queue pair commit a30dc6cf0dc51419021550152e435736aaef8799 upstream. I got a NULL pointer dereference report when doing fuzz test: Call Trace: qp_release_pages+0xae/0x130 qp_host_unregister_user_memory.isra.25+0x2d/0x80 vmci_qp_broker_unmap+0x191/0x320 ? vmci_host_do_alloc_queuepair.isra.9+0x1c0/0x1c0 vmci_host_unlocked_ioctl+0x59f/0xd50 ? do_vfs_ioctl+0x14b/0xa10 ? tomoyo_file_ioctl+0x28/0x30 ? vmci_host_do_alloc_queuepair.isra.9+0x1c0/0x1c0 __x64_sys_ioctl+0xea/0x120 do_syscall_64+0x34/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae When a queue pair is created by the following call, it will not register the user memory if the page_store is NULL, and the entry->state will be set to VMCIQPB_CREATED_NO_MEM. vmci_host_unlocked_ioctl vmci_host_do_alloc_queuepair vmci_qp_broker_alloc qp_broker_alloc qp_broker_create // set entry->state = VMCIQPB_CREATED_NO_MEM; When unmapping this queue pair, qp_host_unregister_user_memory() will be called to unregister the non-existent user memory, which will result in a null pointer reference. It will also change VMCIQPB_CREATED_NO_MEM to VMCIQPB_CREATED_MEM, which should not be present in this operation. Only when the qp broker has mem, it can unregister the user memory when unmapping the qp broker. Only when the qp broker has no mem, it can register the user memory when mapping the qp broker. Fixes: 06164d2b72aa ("VMCI: queue pairs implementation.") Cc: stable Reported-by: Hulk Robot Reviewed-by: Jorgen Hansen Signed-off-by: Wang Hai Link: https://lore.kernel.org/r/20210818124845.488312-1-wanghai38@huawei.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/vmw_vmci/vmci_queue_pair.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c index c2338750313c..a49782dd903c 100644 --- a/drivers/misc/vmw_vmci/vmci_queue_pair.c +++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c @@ -2238,7 +2238,8 @@ int vmci_qp_broker_map(struct vmci_handle handle, result = VMCI_SUCCESS; - if (context_id != VMCI_HOST_CONTEXT_ID) { + if (context_id != VMCI_HOST_CONTEXT_ID && + !QPBROKERSTATE_HAS_MEM(entry)) { struct vmci_qp_page_store page_store; page_store.pages = guest_mem; @@ -2345,7 +2346,8 @@ int vmci_qp_broker_unmap(struct vmci_handle handle, goto out; } - if (context_id != VMCI_HOST_CONTEXT_ID) { + if (context_id != VMCI_HOST_CONTEXT_ID && + QPBROKERSTATE_HAS_MEM(entry)) { qp_acquire_queue_mutex(entry->produce_q); result = qp_save_headers(entry); if (result < VMCI_SUCCESS)