Messages in this thread | | | From | John Keeping <> | Subject | [PATCH 0/6] USB: gadget: f_hid: fix lifetime issues | Date | Thu, 24 Oct 2019 17:45:32 +0100 |
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File descriptors referencing the /dev/hidgN device created by the HID gadget can outlive the underlying gadget function, which creates easy to trigger use-after-frees in the kernel.
A simple reproduction for this using the libusbgx example programs is:
$ gadget-hid $ exec 3<> /dev/hidg0 $ gadget-vid-pid-remove $ exec 3<&-
Closing the file descriptor on the last line triggers a use-after-free which can be seen immediately with slub_debug=P.
This series fixes this by making the struct cdev associated with the module rather than dynamically allocated for the gadget and changing struct f_hidg to be refcounted instead of tied to the gadget lifetime.
John Keeping (6): USB: gadget: f_hid: move chardev setup to module init USB: gadget: f_hid: switch to IDR for tracking minors USB: gadget: f_hid: find f_hidg by IDR lookup on open USB: gadget: f_hid: decouple cdev from f_hidg lifetime USB: gadget: f_hid: refcount f_hidg structure USB: gadget: f_hid: return ENODEV from read/write after deletion
drivers/usb/gadget/function/f_hid.c | 141 +++++++++++++++++++--------- drivers/usb/gadget/function/u_hid.h | 3 - 2 files changed, 95 insertions(+), 49 deletions(-)
-- 2.23.0
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