On 7/31/21 12:44 AM, Pavel Skripkin wrote:

Syzbot reported uninit value pegasus_probe(). The problem was in missing
error handling.

get_interrupt_interval() internally calls read_eprom_word() which can
fail in some cases. For example: failed to receive usb control message.
These cases should be handled to prevent uninit value bug, since
read_eprom_word() will not initialize passed stack variable in case of
internal failure.

Fail log:

BUG: KMSAN: uninit-value in get_interrupt_interval drivers/net/usb/pegasus.c:746 [inline]
BUG: KMSAN: uninit-value in pegasus_probe+0x10e7/0x4080 drivers/net/usb/pegasus.c:1152
CPU: 1 PID: 825 Comm: kworker/1:1 Not tainted 5.12.0-rc6-syzkaller #0
...
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:79 [inline]
  dump_stack+0x24c/0x2e0 lib/dump_stack.c:120
  kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118
  __msan_warning+0x5c/0xa0 mm/kmsan/kmsan_instr.c:197
  get_interrupt_interval drivers/net/usb/pegasus.c:746 [inline]
  pegasus_probe+0x10e7/0x4080 drivers/net/usb/pegasus.c:1152
....

Local variable ----data.i@pegasus_probe created at:
  get_interrupt_interval drivers/net/usb/pegasus.c:1151 [inline]
  pegasus_probe+0xe57/0x4080 drivers/net/usb/pegasus.c:1152
  get_interrupt_interval drivers/net/usb/pegasus.c:1151 [inline]
  pegasus_probe+0xe57/0x4080 drivers/net/usb/pegasus.c:1152

Reported-and-tested-by: syzbot+02c9f70f3afae308464a@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Pavel Skripkin <redacted>
---
  drivers/net/usb/pegasus.c | 14 +++++++++++---
  1 file changed, 11 insertions(+), 3 deletions(-)

Hi, David and Jakub!

Should I rebase this patch on top of Petko's clean-up patches? :

1. https://git.kernel.org/netdev/net/c/8a160e2e9aeb
2. https://git.kernel.org/netdev/net/c/bc65bacf239d



With regards,
Pavel Skripkin