On Thu, 21 Nov 2019, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 46178223 usb: gadget: add raw-gadget interface > git tree: https://github.com/google/kasan.git usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=15a05836e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=99c88c44660624e7 > dashboard link: https://syzkaller.appspot.com/bug?extid=ec5f884c4a135aa0dbb9 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1061395ae00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13653d1ce00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+ec5f884c4a135aa0dbb9@xxxxxxxxxxxxxxxxxxxxxxxxx > > rcu: INFO: rcu_sched self-detected stall on CPU > RIP: 0010:hid_apply_multiplier drivers/hid/hid-core.c:1058 [inline] > RIP: 0010:hid_setup_resolution_multiplier+0x33b/0x990 > drivers/hid/hid-core.c:1114 Diagnostic patch. #syz test: https://github.com/google/kasan.git 46178223 drivers/hid/hid-core.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) Index: usb-devel/drivers/hid/hid-core.c =================================================================== --- usb-devel.orig/drivers/hid/hid-core.c +++ usb-devel/drivers/hid/hid-core.c @@ -1055,8 +1055,13 @@ static void hid_apply_multiplier(struct */ multiplier_collection = &hid->collection[multiplier->usage->collection_index]; while (multiplier_collection->parent_idx != -1 && - multiplier_collection->type != HID_COLLECTION_LOGICAL) + multiplier_collection->type != HID_COLLECTION_LOGICAL) { + hid_info(hid, "collection %d %px parent %d\n", + multiplier_collection - hid->collection, multiplier_collection, + multiplier_collection->parent_idx); multiplier_collection = &hid->collection[multiplier_collection->parent_idx]; + } + hid_info(hid, "Got collection\n"); effective_multiplier = hid_calculate_multiplier(hid, multiplier); @@ -1069,6 +1074,7 @@ static void hid_apply_multiplier(struct effective_multiplier); } } + hid_info(hid, "Applied multiplier\n"); } /* @@ -1103,16 +1109,23 @@ void hid_setup_resolution_multiplier(str rep_enum = &hid->report_enum[HID_FEATURE_REPORT]; list_for_each_entry(rep, &rep_enum->report_list, list) { + hid_info(hid, "Start report %px maxfield %d\n", + rep, rep->maxfield); for (i = 0; i < rep->maxfield; i++) { /* Ignore if report count is out of bounds. */ if (rep->field[i]->report_count < 1) continue; + hid_info(hid, "Field %d %px maxusage %d\n", + i, rep->field[i], rep->field[i]->maxusage); for (j = 0; j < rep->field[i]->maxusage; j++) { usage = &rep->field[i]->usage[j]; - if (usage->hid == HID_GD_RESOLUTION_MULTIPLIER) + if (usage->hid == HID_GD_RESOLUTION_MULTIPLIER) { + hid_info(hid, "Usage %d %px\n", + j, usage); hid_apply_multiplier(hid, rep->field[i]); + } } } }
