Messages in this thread | | | Date | Sun, 19 Dec 2021 01:01:34 +0300 | Subject | Re: [syzbot] KMSAN: uninit-value in asix_mdio_read (2) | From | Pavel Skripkin <> |
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On 12/19/21 00:42, Andrew Lunn wrote: > On Sun, Dec 19, 2021 at 12:14:30AM +0300, Pavel Skripkin wrote: >> On 12/18/21 14:07, syzbot wrote: >> > Hello, >> > >> > syzbot found the following issue on: >> > >> > HEAD commit: b0a8b5053e8b kmsan: core: add dependency on DEBUG_KERNEL >> > git tree: https://github.com/google/kmsan.git master >> > console output: https://syzkaller.appspot.com/x/log.txt?x=13a4d133b00000 >> > kernel config: https://syzkaller.appspot.com/x/.config?x=46a956fc7a887c60 >> > dashboard link: https://syzkaller.appspot.com/bug?extid=f44badb06036334e867a >> > compiler: clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2 >> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=149fddcbb00000 >> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17baef25b00000 >> > >> > IMPORTANT: if you fix the issue, please add the following tag to the commit: >> > Reported-by: syzbot+f44badb06036334e867a@syzkaller.appspotmail.com >> > >> >> The last unhanded case is asix_read_cmd() == 0. Let's handle it... > > That does not look correct, i think. > > asix_read_cmd() == 0 means no error from the read itself. If there is > no error, we should look at the value of smsr and test for bit
As far as I understand asix_read_cmd() == 0 means 0 bytes was read, since it just returns usb_control_msg() return value. I don't know if usb_control_msg() can ever return 0, but looks like it's the only unhanded case
> AX_HOST_EN. Doing a continue means we just ignore the value returned > by the good read. > > I think the correct fix is to look at the value of i. If we have > exceeded 30, we should return -ETIMEDOUT. >
Sorry, I don't get how it can help. Report says, that on following line
else if (smsr & AX_HOST_EN)
smsr is uninitialized. How value of i can help here?
Can you, please, explain if you don't mind :)
Thanks
With regards, Pavel Skripkin
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