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

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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>
This commit is contained in:
Jussi Kivilinna
2009-05-07 17:14:21 -07:00
committed by Dmitry Torokhov
parent d07a9cba6b
commit 9e68177ef9
1 changed files with 1 additions and 1 deletions
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2
drivers/input/ff-memless.c
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@@ -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;