On 15.11.2016 22:36, Guenter Roeck wrote:
The following use-after-free reports were seen on resume with a specific
USB hub.
BUG: KASAN: use-after-free in xhci_free_virt_device+0x8c/0x21c
at addr ffffffc0cc1a2eb0
BUG: KASAN: use-after-free in xhci_update_tt_active_eps+0x9c/0xdc
at addr ffffffc0cc1a2eb0
Relevant traceback for the first case is:
xhci_free_virt_device+0x8c/0x21c
xhci_mem_cleanup+0x294/0x81c
xhci_resume+0x410/0x618
xhci_plat_resume+0x54/0x74
platform_pm_resume+0x74/0x84
which points to the following code in xhci_free_virt_device().
if (dev->tt_info)
old_active_eps = dev->tt_info->active_eps;
Problem with this code is that xhci_mem_cleanup() cleans up devices
starting with slot 1, and dev->tt_info for a device with higher slot
number can point back to the tt_info associated with device 1.
In lsusb, this looks as follows.
/: Bus 05.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
|__ Port 1: Dev 4, If 0, Class=Hub, Driver=hub/4p, 480M
|__ Port 3: Dev 7, If 0, Class=Vendor Specific Class, Driver=, 12M
When the higher-numbered device is cleared, it tries to access the already
released tt_info from slot 1 to get the value of old_active_eps.
The problem is not seen with all USB hubs since not all USB hubs require
the cleanup handling in xhci_resume().
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
Thanks, nice catch.
Marked as RFC because I don't really like this fix at all and would prefer
a different solution.
I just started digging into this and see if I can come up with some solution.
It's currently a bit messy the whole thing how the tt_info and bw_table are
allocated, freed, pointed to and added and removed to/from lists
-Mathias
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