syzbot is reporting too large allocation at input_mt_init_slots(), for num_slots is supplied from userspace using ioctl(UI_DEV_CREATE). Use __GFP_NOWARN. Also, replace n2 with array_size(), for 32bits variable n2 will overflow if num_slots >= 65536 and will cause out of bounds read/write at input_mt_set_matrix()/input_mt_set_slots() on architectures where PAGE_SIZE > 4096 is available (e.g. PPC64). Reported-by: syzbot <syzbot+0122fa359a69694395d5@xxxxxxxxxxxxxxxxxxxxxxxxx> Link: https://syzkaller.appspot.com/bug?extid=0122fa359a69694395d5 Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> --- Dmitry Torokhov proposed limiting max size to accept. But since it seems that nobody knows appropriate max size to accept, reposting as-is. https://lkml.kernel.org/r/03e8c3f0-bbbf-af37-6f52-67547cbd4cde@xxxxxxxxxxxxxxxxxxx drivers/input/input-mt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c index 14b53dac1253..cf74579462ba 100644 --- a/drivers/input/input-mt.c +++ b/drivers/input/input-mt.c @@ -47,7 +47,7 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots, if (mt) return mt->num_slots != num_slots ? -EINVAL : 0; - mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL); + mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL | __GFP_NOWARN); if (!mt) goto err_mem; @@ -80,8 +80,8 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots, if (flags & INPUT_MT_SEMI_MT) __set_bit(INPUT_PROP_SEMI_MT, dev->propbit); if (flags & INPUT_MT_TRACK) { - unsigned int n2 = num_slots * num_slots; - mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL); + mt->red = kcalloc(array_size(num_slots, num_slots), + sizeof(*mt->red), GFP_KERNEL | __GFP_NOWARN); if (!mt->red) goto err_mem; } -- 2.18.4
