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The snd_usb_copy_string_desc() retrieves the usb string corresponding to the index number through the usb_string(). The problem is that the usb_string() returns the length of the string (>= 0) when successful, but it can also return a negative value about the error case or status of usb_control_msg(). If iClockSource is '0' as shown below, usb_string() will returns -EINVAL. This will result in '0' being inserted into buf[-22], and the following KASAN out-of-bound error message will be output. AudioControl Interface Descriptor: bLength 8 bDescriptorType 36 bDescriptorSubtype 10 (CLOCK_SOURCE) bClockID 1 bmAttributes 0x07 Internal programmable Clock (synced to SOF) bmControls 0x07 Clock Frequency Control (read/write) Clock Validity Control (read-only) bAssocTerminal 0 iClockSource 0 To fix it, check usb_string()'return value and bail out. ================================================================== BUG: KASAN: stack-out-of-bounds in parse_audio_unit+0x1327/0x1960 [snd_usb_audio] Write of size 1 at addr ffff88007e66735a by task systemd-udevd/18376 CPU: 0 PID: 18376 Comm: systemd-udevd Not tainted 4.13.0+ #3 Hardware name: LG Electronics 15N540-RFLGL/White Tip Mountain, BIOS 15N5 Call Trace: dump_stack+0x63/0x8d print_address_description+0x70/0x290 ? parse_audio_unit+0x1327/0x1960 [snd_usb_audio] kasan_report+0x265/0x350 __asan_store1+0x4a/0x50 parse_audio_unit+0x1327/0x1960 [snd_usb_audio] ? save_stack+0xb5/0xd0 ? save_stack_trace+0x1b/0x20 ? save_stack+0x46/0xd0 ? kasan_kmalloc+0xad/0xe0 ? kmem_cache_alloc_trace+0xff/0x230 ? snd_usb_create_mixer+0xb0/0x4b0 [snd_usb_audio] ? usb_audio_probe+0x4de/0xf40 [snd_usb_audio] ? usb_probe_interface+0x1f5/0x440 ? driver_probe_device+0x3ed/0x660 ? build_feature_ctl+0xb10/0xb10 [snd_usb_audio] ? save_stack_trace+0x1b/0x20 ? init_object+0x69/0xa0 ? snd_usb_find_csint_desc+0xa8/0xf0 [snd_usb_audio] snd_usb_mixer_controls+0x1dc/0x370 [snd_usb_audio] ? build_audio_procunit+0x890/0x890 [snd_usb_audio] ? snd_usb_create_mixer+0xb0/0x4b0 [snd_usb_audio] ? kmem_cache_alloc_trace+0xff/0x230 ? usb_ifnum_to_if+0xbd/0xf0 snd_usb_create_mixer+0x25b/0x4b0 [snd_usb_audio] ? snd_usb_create_stream+0x255/0x2c0 [snd_usb_audio] usb_audio_probe+0x4de/0xf40 [snd_usb_audio] ? snd_usb_autosuspend.part.7+0x30/0x30 [snd_usb_audio] ? __pm_runtime_idle+0x90/0x90 ? kernfs_activate+0xa6/0xc0 ? usb_match_one_id_intf+0xdc/0x130 ? __pm_runtime_set_status+0x2d4/0x450 usb_probe_interface+0x1f5/0x440 Cc: <stable@vger.kernel.org> Signed-off-by: Jaejoong Kim <climbbb.kim@gmail.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.