3.16.78-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Suzuki K Poulose suzuki.poulose@arm.com
commit fc05481b2fcabaaeccf63e32ac1baab54e5b6963 upstream.
syzbot reported the following crash [0]:
BUG: KASAN: use-after-free in usb_free_coherent+0x79/0x80 drivers/usb/core/usb.c:928 Read of size 8 at addr ffff8881b18599c8 by task syz-executor.4/16007
CPU: 0 PID: 16007 Comm: syz-executor.4 Not tainted 5.3.0-rc2+ #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xca/0x13e lib/dump_stack.c:113 print_address_description+0x6a/0x32c mm/kasan/report.c:351 __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482 kasan_report+0xe/0x12 mm/kasan/common.c:612 usb_free_coherent+0x79/0x80 drivers/usb/core/usb.c:928 yurex_delete+0x138/0x330 drivers/usb/misc/yurex.c:100 kref_put include/linux/kref.h:65 [inline] yurex_release+0x66/0x90 drivers/usb/misc/yurex.c:392 __fput+0x2d7/0x840 fs/file_table.c:280 task_work_run+0x13f/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:274 [inline] do_syscall_64+0x45f/0x580 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x413511 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffc424ea2e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000413511 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006 RBP: 0000000000000001 R08: 0000000029a2fc22 R09: 0000000029a2fc26 R10: 00007ffc424ea3c0 R11: 0000000000000293 R12: 000000000075c9a0 R13: 000000000075c9a0 R14: 0000000000761938 R15: ffffffffffffffff
Allocated by task 2776: save_stack+0x1b/0x80 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:487 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:460 kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:748 [inline] usb_alloc_dev+0x51/0xf95 drivers/usb/core/usb.c:583 hub_port_connect drivers/usb/core/hub.c:5004 [inline] hub_port_connect_change drivers/usb/core/hub.c:5213 [inline] port_event drivers/usb/core/hub.c:5359 [inline] hub_event+0x15c0/0x3640 drivers/usb/core/hub.c:5441 process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 worker_thread+0x96/0xe20 kernel/workqueue.c:2415 kthread+0x318/0x420 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Freed by task 16007: save_stack+0x1b/0x80 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_slab_free+0x130/0x180 mm/kasan/common.c:449 slab_free_hook mm/slub.c:1423 [inline] slab_free_freelist_hook mm/slub.c:1470 [inline] slab_free mm/slub.c:3012 [inline] kfree+0xe4/0x2f0 mm/slub.c:3953 device_release+0x71/0x200 drivers/base/core.c:1064 kobject_cleanup lib/kobject.c:693 [inline] kobject_release lib/kobject.c:722 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x171/0x280 lib/kobject.c:739 put_device+0x1b/0x30 drivers/base/core.c:2213 usb_put_dev+0x1f/0x30 drivers/usb/core/usb.c:725 yurex_delete+0x40/0x330 drivers/usb/misc/yurex.c:95 kref_put include/linux/kref.h:65 [inline] yurex_release+0x66/0x90 drivers/usb/misc/yurex.c:392 __fput+0x2d7/0x840 fs/file_table.c:280 task_work_run+0x13f/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:274 [inline] do_syscall_64+0x45f/0x580 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff8881b1859980 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 72 bytes inside of 2048-byte region [ffff8881b1859980, ffff8881b185a180) The buggy address belongs to the page: page:ffffea0006c61600 refcount:1 mapcount:0 mapping:ffff8881da00c000 index:0x0 compound_mapcount: 0 flags: 0x200000000010200(slab|head) raw: 0200000000010200 0000000000000000 0000000100000001 ffff8881da00c000 raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8881b1859880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881b1859900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881b1859980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8881b1859a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881b1859a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
A quick look at the yurex_delete() shows that we drop the reference to the usb_device before releasing any buffers associated with the device. Delay the reference drop until we have finished the cleanup.
[0] https://lore.kernel.org/lkml/0000000000003f86d8058f0bd671@google.com/
Fixes: 6bc235a2e24a5e ("USB: add driver for Meywa-Denki & Kayac YUREX") Cc: Jiri Kosina jkosina@suse.cz Cc: Tomoki Sekiyama tomoki.sekiyama@gmail.com Cc: Oliver Neukum oneukum@suse.com Cc: andreyknvl@google.com Cc: gregkh@linuxfoundation.org Cc: Alan Stern stern@rowland.harvard.edu Cc: syzkaller-bugs@googlegroups.com Cc: dtor@chromium.org Reported-by: syzbot+d1fedb1c1fdb07fca507@syzkaller.appspotmail.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Link: https://lore.kernel.org/r/20190805111528.6758-1-suzuki.poulose@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/misc/yurex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -96,7 +96,6 @@ static void yurex_delete(struct kref *kr
dev_dbg(&dev->interface->dev, "%s\n", __func__);
- usb_put_dev(dev->udev); if (dev->cntl_urb) { usb_kill_urb(dev->cntl_urb); kfree(dev->cntl_req); @@ -112,6 +111,7 @@ static void yurex_delete(struct kref *kr dev->int_buffer, dev->urb->transfer_dma); usb_free_urb(dev->urb); } + usb_put_dev(dev->udev); kfree(dev); }