Commit 9e68177e authored May 07, 2009 by Jussi Kivilinna Committed by Dmitry Torokhov May 07, 2009

Input: ff-memless - fix signed to unsigned bit overflow



When userspace sets effect->u.rumble.strong_magnitude to 0x8001 or
larger, ml_combine_effects() would always return strong_magnitude
0xffff.

Problem is that 'gain' is passed in as signed integer. Multiplying
magnitude (__u16) with gain (int) causes magnitude read as signed and
results negative value (with magnitude > 0x8000). This signed integer
is then divided and value, still negative, converted to 32bit unsigned
integer. Finally checking combine overflow min(new+old, 0xffff) gives
out 0xffff.

Fix is to simply change 'gain' to unsigned int.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Acked-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

parent d07a9cba

drivers/input/ff-memless.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -226,7 +226,7 @@ static int get_compatible_type(struct ff_device *ff, int effect_type)
	*/		*/
	static void ml_combine_effects(struct ff_effect *effect,		static void ml_combine_effects(struct ff_effect *effect,
	struct ml_effect_state *state,		struct ml_effect_state *state,
	int gain)		unsigned int gain)
	{		{
	struct ff_effect *new = state->effect;		struct ff_effect *new = state->effect;
	unsigned int strong, weak, i;		unsigned int strong, weak, i;