USB: chaoskey: Fix slab-use-after-free in chaoskey_release()

The chaoskey driver has a use-after-free bug in its release routine.
If the user closes the device file after the USB device has been
unplugged, a debugging log statement will try to access the
usb_interface structure after it has been deallocated:

	BUG: KASAN: slab-use-after-free in dev_driver_string (drivers/base/core.c:2406)
	Read of size 8 at addr ffff888168e8a0b8 by task chaoskey_raw_re/10106

	Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
	Call Trace:
	 <TASK>
	 dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
	 print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
	 kasan_report (mm/kasan/report.c:595)
	 dev_driver_string (drivers/base/core.c:2406)
	 __dynamic_dev_dbg (lib/dynamic_debug.c:906)
	 chaoskey_release (drivers/usb/misc/chaoskey.c:323)
	 __fput (fs/file_table.c:510)
	 fput_close_sync (fs/file_table.c:615)
	 __x64_sys_close (fs/open.c:1507 fs/open.c:1492 fs/open.c:1492)
	 do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
	 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)

The driver's last reference to the interface structure is dropped in
the chaoskey_free() routine, so the code must not use the interface --
even in a debugging statement -- after that routine returns.
(Exception: If we know that another reference is held by someone else,
such as the device core while the disconnect routine runs, there's no
problem.  Thanks to Johan Hovold for pointing this out.)

Since the bad access is part of an unimportant debugging statement,
we can fix the problem simply by removing the whole statement.

Reported-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Closes: https://lore.kernel.org/linux-usb/20EC9664-054E-438B-B411-2145D347F97B@gmail.com/
Tested-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: 66e3e591891d ("usb: Add driver for Altus Metrum ChaosKey device (v2)")
Cc: stable <stable@kernel.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/bb5b1dc6-eb59-43e1-8d26-51e658e88bbe@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index d8016540953fcd4f560c5d33731349b983801570..9c06f7775301f588b034c14a29d653db069a798d 100644 (file)
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -320,7 +320,6 @@ bail:
        mutex_unlock(&dev->lock);
 destruction:
        mutex_unlock(&chaoskey_list_lock);
-       usb_dbg(interface, "release success");
        return rv;
 }