On Mon, 29 Apr 2019, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 43151d6c usb-fuzzer: main usb gadget fuzzer driver > git tree: https://github.com/google/kasan/tree/usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=139ac37f200000 > kernel config: https://syzkaller.appspot.com/x/.config?x=4183eeef650d1234 > dashboard link: https://syzkaller.appspot.com/bug?extid=a9fefd18c7b240f19c54 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17f3b338a00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+a9fefd18c7b240f19c54@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: slab-out-of-bounds in hex_string+0x418/0x4b0 lib/vsprintf.c:975 > Read of size 1 at addr ffff88821a41bd38 by task kworker/0:1/12 > > CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0-rc3-319004-g43151d6 #6 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Workqueue: usb_hub_wq hub_event > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xe8/0x16e lib/dump_stack.c:113 > print_address_description+0x6c/0x236 mm/kasan/report.c:187 > kasan_report.cold+0x1a/0x3c mm/kasan/report.c:317 > hex_string+0x418/0x4b0 lib/vsprintf.c:975 > pointer+0x460/0x910 lib/vsprintf.c:1985 > vsnprintf+0x5a0/0x16b0 lib/vsprintf.c:2400 > pointer+0x60b/0x910 lib/vsprintf.c:2038 > vsnprintf+0x5a0/0x16b0 lib/vsprintf.c:2400 > vscnprintf+0x29/0x80 lib/vsprintf.c:2499 > vprintk_store+0x45/0x4b0 kernel/printk/printk.c:1900 > vprintk_emit+0x210/0x5a0 kernel/printk/printk.c:1957 > dev_vprintk_emit+0x50e/0x553 drivers/base/core.c:3185 > dev_printk_emit+0xbf/0xf6 drivers/base/core.c:3196 > __dev_printk+0x1ed/0x215 drivers/base/core.c:3208 > _dev_info+0xdc/0x10e drivers/base/core.c:3254 > dlfb_parse_vendor_descriptor drivers/video/fbdev/udlfb.c:1532 [inline] Accessing beyond the end of the descriptor. #syz test: https://github.com/google/kasan.git usb-fuzzer --- a/drivers/video/fbdev/udlfb.c +++ b/drivers/video/fbdev/udlfb.c @@ -1511,6 +1511,7 @@ static int dlfb_parse_vendor_descriptor( char *buf; char *desc_end; int total_len; + int width; buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL); if (!buf) @@ -1529,9 +1530,10 @@ static int dlfb_parse_vendor_descriptor( } if (total_len > 5) { + width = min(total_len, 11); dev_info(&intf->dev, - "vendor descriptor length: %d data: %11ph\n", - total_len, desc); + "vendor descriptor length: %d data: %*ph\n", + total_len, width, desc); if ((desc[0] != total_len) || /* descriptor length */ (desc[1] != 0x5f) || /* vendor descriptor type */
