IB/uverbs: Fix OOPs upon device disassociation

yishaih · jgunthorpe · commit 425784aa5b02 · 2019-01-25T11:58:06.000-07:00
The async_file might be freed before the disassociation has been ended, causing qp shutdown to use after free on it. Since uverbs_destroy_ufile_hw is not a fence, it returns if a disassociation is ongoing in another thread. It has to be written this way to avoid deadlock. However this means that the ufile FD close cannot destroy anything that may still be used by an active kref, such as the the async_file. To fix that move the kref_put() to be in ib_uverbs_release_file(). BUG: unable to handle kernel paging request at ffffffffba682787 PGD bc80e067 P4D bc80e067 PUD bc80f063 PMD 1313df163 PTE 80000000bc682061 Oops: 0003 [#1] SMP PTI CPU: 1 PID: 32410 Comm: bash Tainted: G OE 4.20.0-rc6+ #3 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 RIP: 0010:__pv_queued_spin_lock_slowpath+0x1b3/0x2a0 Code: 98 83 e2 60 49 89 df 48 8b 04 c5 80 18 72 ba 48 8d ba 80 32 02 00 ba 00 80 00 00 4c 8d 65 14 41 bd 01 00 00 00 48 01 c7 85 d2 <48> 89 2f 48 89 fb 74 14 8b 45 08 85 c0 75 42 84 d2 74 6b f3 90 83 RSP: 0018:ffffc1bbc064fb58 EFLAGS: 00010006 RAX: ffffffffba65f4e7 RBX: ffff9f209c656c00 RCX: 0000000000000001 RDX: 0000000000008000 RSI: 0000000000000000 RDI: ffffffffba682787 RBP: ffff9f217bb23280 R08: 0000000000000001 R09: 0000000000000000 R10: ffff9f209d2c7800 R11: ffffffffffffffe8 R12: ffff9f217bb23294 R13: 0000000000000001 R14: 0000000000000000 R15: ffff9f209c656c00 FS: 00007fac55aad740(0000) GS:ffff9f217bb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffba682787 CR3: 000000012f8e0000 CR4: 00000000000006e0 Call Trace: _raw_spin_lock_irq+0x27/0x30 ib_uverbs_release_uevent+0x1e/0xa0 [ib_uverbs] uverbs_free_qp+0x7e/0x90 [ib_uverbs] destroy_hw_idr_uobject+0x1c/0x50 [ib_uverbs] uverbs_destroy_uobject+0x2e/0x180 [ib_uverbs] __uverbs_cleanup_ufile+0x73/0x90 [ib_uverbs] uverbs_destroy_ufile_hw+0x5d/0x120 [ib_uverbs] ib_uverbs_remove_one+0xea/0x240 [ib_uverbs] ib_unregister_device+0xfb/0x200 [ib_core] mlx5_ib_remove+0x51/0xe0 [mlx5_ib] mlx5_remove_device+0xc1/0xd0 [mlx5_core] mlx5_unregister_device+0x3d/0xb0 [mlx5_core] remove_one+0x2a/0x90 [mlx5_core] pci_device_remove+0x3b/0xc0 device_release_driver_internal+0x16d/0x240 unbind_store+0xb2/0x100 kernfs_fop_write+0x102/0x180 __vfs_write+0x36/0x1a0 ? __alloc_fd+0xa9/0x170 ? set_close_on_exec+0x49/0x70 vfs_write+0xad/0x1a0 ksys_write+0x52/0xc0 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fac551aac60 Cc: <stable@vger.kernel.org> # 4.2 Fixes: 036b106 ("IB/uverbs: Enable device removal when there are active user space applications") Signed-off-by: Yishai Hadas <yishaih@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
@@ -204,6 +204,9 @@ void ib_uverbs_release_file(struct kref *ref)
 	if (atomic_dec_and_test(&file->device->refcount))
 		ib_uverbs_comp_dev(file->device);
 
+	if (file->async_file)
+		kref_put(&file->async_file->ref,
+			 ib_uverbs_release_async_event_file);
 	put_device(&file->device->dev);
 	kfree(file);
 }
@@ -1096,10 +1099,6 @@ static int ib_uverbs_close(struct inode *inode, struct file *filp)
 	list_del_init(&file->list);
 	mutex_unlock(&file->device->lists_mutex);
 
-	if (file->async_file)
-		kref_put(&file->async_file->ref,
-			 ib_uverbs_release_async_event_file);
-
 	kref_put(&file->ref, ib_uverbs_release_file);
 
 	return 0;
