| Message ID | 20210202120807.1394788-1-snovitoll@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | drivers/mt: restrict length of kzalloc in input_mt_init_slots() | expand |
On Tue, 2 Feb 2021 18:08:07 +0600, Sabyrzhan Tasbolatov wrote: > syzbot found WARNING in input_mt_init_slots [1] when > struct_size(mt, slots, num_slots)=0x40006 where num_slots=0x10001, > which exceeds KMALLOC_MAX_SIZE (0x40000) and causes > order >= MAX_ORDER condition. > > [1] > Call Trace: > alloc_pages_current+0x18c/0x2a0 mm/mempolicy.c:2267 > alloc_pages include/linux/gfp.h:547 [inline] > kmalloc_order+0x2e/0xb0 mm/slab_common.c:837 > kmalloc_order_trace+0x14/0x120 mm/slab_common.c:853 > kmalloc include/linux/slab.h:557 [inline] > kzalloc include/linux/slab.h:682 [inline] > input_mt_init_slots drivers/input/input-mt.c:49 [inline] > > Reported-by: syzbot+0122fa359a69694395d5@syzkaller.appspotmail.com > Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com> > --- > drivers/input/input-mt.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c > index 44fe6f2f063c..e542f45a45ab 100644 > --- a/drivers/input/input-mt.c > +++ b/drivers/input/input-mt.c > @@ -40,13 +40,18 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots, > { > struct input_mt *mt = dev->mt; > int i; > + size_t mt_size = 0; > > if (!num_slots) > return 0; > if (mt) > return mt->num_slots != num_slots ? -EINVAL : 0; > > - mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL); > + mt_size = struct_size(mt, slots, num_slots); > + if (mt_size > KMALLOC_MAX_SIZE) > + return -ENOMEM; > + > + mt = kzalloc(mt_size, GFP_KERNEL); > if (!mt) > goto err_mem; > > -- Following-up. I've also just found out that in this function, there is another allocation with num_slots length: int input_mt_init_slots(..) { .. if (flags & INPUT_MT_TRACK) { unsigned int n2 = num_slots * num_slots; mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL); .. I've checked HID vendors' xrefs for input_mt_init_slots(), most of them pass >= 5 value to num_slots parameter. So either we should choose some optimal limit of num_slots or just restrict it with big KMALLOC_MAX_SIZE. Comments?
diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c index 44fe6f2f063c..e542f45a45ab 100644 --- a/drivers/input/input-mt.c +++ b/drivers/input/input-mt.c @@ -40,13 +40,18 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots, { struct input_mt *mt = dev->mt; int i; + size_t mt_size = 0; if (!num_slots) return 0; if (mt) return mt->num_slots != num_slots ? -EINVAL : 0; - mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL); + mt_size = struct_size(mt, slots, num_slots); + if (mt_size > KMALLOC_MAX_SIZE) + return -ENOMEM; + + mt = kzalloc(mt_size, GFP_KERNEL); if (!mt) goto err_mem;
syzbot found WARNING in input_mt_init_slots [1] when struct_size(mt, slots, num_slots)=0x40006 where num_slots=0x10001, which exceeds KMALLOC_MAX_SIZE (0x40000) and causes order >= MAX_ORDER condition. [1] Call Trace: alloc_pages_current+0x18c/0x2a0 mm/mempolicy.c:2267 alloc_pages include/linux/gfp.h:547 [inline] kmalloc_order+0x2e/0xb0 mm/slab_common.c:837 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:853 kmalloc include/linux/slab.h:557 [inline] kzalloc include/linux/slab.h:682 [inline] input_mt_init_slots drivers/input/input-mt.c:49 [inline] Reported-by: syzbot+0122fa359a69694395d5@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com> --- drivers/input/input-mt.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)