Re: [PATCH v4.14.y] HID: debug: fix the ring buffer implementation

[Guenter Roeck <linux@roeck-us.net>]

On 2/13/19 6:18 AM, Greg Kroah-Hartman wrote:
> On Mon, Feb 11, 2019 at 09:26:25AM -0800, Guenter Roeck wrote:
>> From: Vladis Dronov <vdronov@redhat.com>
>>
>> commit 13054abbaa4f1fd4e6f3b4b63439ec033b4c8035 upstream.
>>
>> Ring buffer implementation in hid_debug_event() and hid_debug_events_read()
>> is strange allowing lost or corrupted data. After commit 717adfdaf147
>> ("HID: debug: check length before copy_to_user()") it is possible to enter
>> an infinite loop in hid_debug_events_read() by providing 0 as count, this
>> locks up a system. Fix this by rewriting the ring buffer implementation
>> with kfifo and simplify the code.
>>
>> This fixes CVE-2019-3819.
>>
>> v2: fix an execution logic and add a comment
>> v3: use __set_current_state() instead of set_current_state()
>>
>> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1669187
>> Fixes: cd667ce24796 ("HID: use debugfs for events/reports dumping")
>> Fixes: 717adfdaf147 ("HID: debug: check length before copy_to_user()")
>> Signed-off-by: Vladis Dronov <vdronov@redhat.com>
>> Reviewed-by: Oleg Nesterov <oleg@redhat.com>
>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> [groeck: backport to v4.14.y]
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> ---
>> This patch is marked v4.18+, but commit 717adfdaf147 is marked for stable
>> and found its way into all stable releases. Therefore, this patch is needed
>> in older stable releases as well. This patch only applies to v4.14.y;
>> backport to v4.9.y will follow.
>>
>> Copying patch author and reviewers to make sure I didn't miss anything.
>>
>>   drivers/hid/hid-debug.c   | 121 ++++++++++++++++++----------------------------
>>   include/linux/hid-debug.h |   9 ++--
>>   2 files changed, 51 insertions(+), 79 deletions(-)
> 
> Vladis sent backports that are a bit different from yours, so I'll go
> with his now :)
> 

NP, and preferred, as long as the problem is getting fixed ...

Guenter