Andrey Konovalov <andreyknvl@xxxxxxxxxx> writes: > On Mon, Sep 25, 2017 at 6:26 AM, Kalle Valo <kvalo@xxxxxxxxxxxxxx> wrote: >> Andrey Konovalov <andreyknvl@xxxxxxxxxx> writes: >> >>> I've got the following report while fuzzing the kernel with syzkaller. >>> >>> On commit 6e80ecdddf4ea6f3cd84e83720f3d852e6624a68 (Sep 21). >>> >>> ================================================================== >>> BUG: KASAN: use-after-free in __run_timers+0xc0e/0xd40 >>> Write of size 8 at addr ffff880069f701b8 by task swapper/0/0 >>> >>> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc1-42311-g6e80ecdddf4e #234 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> >> [...] >> >>> Allocated by task 1845: >>> save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:447 >>> set_track mm/kasan/kasan.c:459 >>> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 >>> kmem_cache_alloc_trace+0x11e/0x2d0 mm/slub.c:2772 >>> kmalloc ./include/linux/slab.h:493 >>> kzalloc ./include/linux/slab.h:666 >>> rsi_91x_init+0x98/0x510 drivers/net/wireless/rsi/rsi_91x_main.c:203 >>> rsi_probe+0xb6/0x13b0 drivers/net/wireless/rsi/rsi_91x_usb.c:665 >>> usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361 >> >> I'm curious about your setup. Apparently you are running syzkaller on >> QEMU but what I don't understand is how the rsi device comes into the >> picture. Did you have a rsi usb device connected to the virtual machine >> or what? Or does syzkaller do some kind of magic here? > > I use dummy_hcd and gadgetfs to connect random USB devices to the > kernel from a userspace application. This happens inside a QEMU > instance. This simplifies fuzzing, since everything is virtualized, > but the found bugs can be triggered on a real machine by connecting a > malicious USB device. That's very cool, thanks for explaining the setup. -- Kalle Valo
