On Mon, 9 Dec 2019, syzbot wrote: > Hello, > > syzbot has tested the proposed patch but the reproducer still triggered > crash: > KASAN: slab-out-of-bounds Read in hid_field_extract > > microsoft 0003:045E:07DA.0001: Report rsize 4096 csize 1 > microsoft 0003:045E:07DA.0001: Field offset 0 size 12 count 4899 > ================================================================== > BUG: KASAN: slab-out-of-bounds in __extract drivers/hid/hid-core.c:1345 > [inline] > BUG: KASAN: slab-out-of-bounds in hid_field_extract+0x150/0x170 > drivers/hid/hid-core.c:1365 > Read of size 1 at addr ffff8881cc759000 by task swapper/1/0 Nobody bothers to check for ridiculously long reports? This field had report_size = 12 and report_count = 4899! Alan Stern #syz test: https://github.com/google/kasan.git 1f22d15c Index: usb-devel/drivers/hid/hid-core.c =================================================================== --- usb-devel.orig/drivers/hid/hid-core.c +++ usb-devel/drivers/hid/hid-core.c @@ -267,6 +267,10 @@ static int hid_add_field(struct hid_pars offset = report->size; report->size += parser->global.report_size * parser->global.report_count; + if (report->size > HID_MAX_BUFFER_SIZE << 3) { + hid_err(parser->device, "report is too long\n"); + return -1; + } if (!parser->local.usage_index) /* Ignore padding fields */ return 0; @@ -1488,6 +1492,7 @@ static void hid_input_field(struct hid_d if (!value) return; + hid_info(hid, "Field offset %u size %u count %u\n", offset, size, count); for (n = 0; n < count; n++) { value[n] = min < 0 ? @@ -1712,6 +1717,7 @@ int hid_report_raw_event(struct hid_devi } if (hid->claimed != HID_CLAIMED_HIDRAW && report->maxfield) { + hid_info(hid, "Report rsize %u csize %u\n", rsize, csize); for (a = 0; a < report->maxfield; a++) hid_input_field(hid, report->field[a], cdata, interrupt); hdrv = hid->driver;
