From 1af4f24cb6708615f5a0eb30f2fcfcdcc0f1766e Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Sat, 19 Mar 2016 11:05:18 +0100 Subject: [PATCH] Bluetooth: vhci: fix open_timeout vs. hdev race commit 373a32c848ae3a1c03618517cce85f9211a6facf upstream. Both vhci_get_user and vhci_release race with open_timeout work. They both contain cancel_delayed_work_sync, but do not test whether the work actually created hdev or not. Since the work can be in progress and _sync will wait for finishing it, we can have data->hdev allocated when cancel_delayed_work_sync returns. But the call sites do 'if (data->hdev)' *before* cancel_delayed_work_sync. As a result: * vhci_get_user allocates a second hdev and puts it into data->hdev. The former is leaked. * vhci_release does not release data->hdev properly as it thinks there is none. Fix both cases by moving the actual test *after* the call to cancel_delayed_work_sync. This can be hit by this program: #include #include #include #include #include #include #include #include int main(int argc, char **argv) { int fd; srand(time(NULL)); while (1) { const int delta = (rand() % 200 - 100) * 100; fd = open("/dev/vhci", O_RDWR); if (fd < 0) err(1, "open"); usleep(1000000 + delta); close(fd); } return 0; } And the result is: BUG: KASAN: use-after-free in skb_queue_tail+0x13e/0x150 at addr ffff88006b0c1228 Read of size 8 by task kworker/u13:1/32068 ============================================================================= BUG kmalloc-192 (Tainted: G E ): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in vhci_open+0x50/0x330 [hci_vhci] age=260 cpu=3 pid=32040 ... kmem_cache_alloc_trace+0x150/0x190 vhci_open+0x50/0x330 [hci_vhci] misc_open+0x35b/0x4e0 chrdev_open+0x23b/0x510 ... INFO: Freed in vhci_release+0xa4/0xd0 [hci_vhci] age=9 cpu=2 pid=32040 ... __slab_free+0x204/0x310 vhci_release+0xa4/0xd0 [hci_vhci] ... INFO: Slab 0xffffea0001ac3000 objects=16 used=13 fp=0xffff88006b0c1e00 flags=0x5fffff80004080 INFO: Object 0xffff88006b0c1200 @offset=4608 fp=0xffff88006b0c0600 Bytes b4 ffff88006b0c11f0: 09 df 00 00 01 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff88006b0c1200: 00 06 0c 6b 00 88 ff ff 00 00 00 00 00 00 00 00 ...k............ Object ffff88006b0c1210: 10 12 0c 6b 00 88 ff ff 10 12 0c 6b 00 88 ff ff ...k.......k.... Object ffff88006b0c1220: c0 46 c2 6b 00 88 ff ff c0 46 c2 6b 00 88 ff ff .F.k.....F.k.... Object ffff88006b0c1230: 01 00 00 00 01 00 00 00 e0 ff ff ff 0f 00 00 00 ................ Object ffff88006b0c1240: 40 12 0c 6b 00 88 ff ff 40 12 0c 6b 00 88 ff ff @..k....@..k.... Object ffff88006b0c1250: 50 0d 6e a0 ff ff ff ff 00 02 00 00 00 00 ad de P.n............. Object ffff88006b0c1260: 00 00 00 00 00 00 00 00 ab 62 02 00 01 00 00 00 .........b...... Object ffff88006b0c1270: 90 b9 19 81 ff ff ff ff 38 12 0c 6b 00 88 ff ff ........8..k.... Object ffff88006b0c1280: 03 00 20 00 ff ff ff ff ff ff ff ff 00 00 00 00 .. ............. Object ffff88006b0c1290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ Object ffff88006b0c12a0: 00 00 00 00 00 00 00 00 00 80 cd 3d 00 88 ff ff ...........=.... Object ffff88006b0c12b0: 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 . .............. Redzone ffff88006b0c12c0: bb bb bb bb bb bb bb bb ........ Padding ffff88006b0c13f8: 00 00 00 00 00 00 00 00 ........ CPU: 3 PID: 32068 Comm: kworker/u13:1 Tainted: G B E 4.4.6-0-default #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20151112_172657-sheep25 04/01/2014 Workqueue: hci0 hci_cmd_work [bluetooth] 00000000ffffffff ffffffff81926cfa ffff88006be37c68 ffff88006bc27180 ffff88006b0c1200 ffff88006b0c1234 ffffffff81577993 ffffffff82489320 ffff88006bc24240 0000000000000046 ffff88006a100000 000000026e51eb80 Call Trace: ... [] ? skb_queue_tail+0x13e/0x150 [] ? vhci_send_frame+0xac/0x100 [hci_vhci] [] ? hci_send_frame+0x188/0x320 [bluetooth] [] ? hci_cmd_work+0x115/0x310 [bluetooth] [] ? process_one_work+0x815/0x1340 [] ? worker_thread+0xe5/0x11f0 [] ? process_one_work+0x1340/0x1340 [] ? kthread+0x1c8/0x230 ... Memory state around the buggy address: ffff88006b0c1100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88006b0c1180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88006b0c1200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88006b0c1280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88006b0c1300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc Fixes: 23424c0d31 (Bluetooth: Add support creating virtual AMP controllers) Signed-off-by: Jiri Slaby Signed-off-by: Marcel Holtmann Cc: Dmitry Vyukov Signed-off-by: Greg Kroah-Hartman --- drivers/bluetooth/hci_vhci.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c index ed888e3..b6fb499 100644 --- a/drivers/bluetooth/hci_vhci.c +++ b/drivers/bluetooth/hci_vhci.c @@ -189,13 +189,13 @@ static inline ssize_t vhci_get_user(struct vhci_data *data, break; case HCI_VENDOR_PKT: + cancel_delayed_work_sync(&data->open_timeout); + if (data->hdev) { kfree_skb(skb); return -EBADFD; } - cancel_delayed_work_sync(&data->open_timeout); - opcode = *((__u8 *) skb->data); skb_pull(skb, 1); @@ -333,10 +333,12 @@ static int vhci_open(struct inode *inode, struct file *file) static int vhci_release(struct inode *inode, struct file *file) { struct vhci_data *data = file->private_data; - struct hci_dev *hdev = data->hdev; + struct hci_dev *hdev; cancel_delayed_work_sync(&data->open_timeout); + hdev = data->hdev; + if (hdev) { hci_unregister_dev(hdev); hci_free_dev(hdev); -- 2.7.4