Re: [PATCH v2] net: usb: dm9601: fix uninitialized variable use in dm9601_mdio_read

[Greg KH]

On Tue, Oct 10, 2023 at 09:22:49AM +0200, Peter Korsgaard wrote:
> >>>>> "Greg" == Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> writes:
> 
>  > On Tue, Oct 10, 2023 at 08:19:48AM +0200, Peter Korsgaard wrote:
>  >> >>>>> "Greg" == Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> writes:
>  >> 
>  >> > On Tue, Oct 10, 2023 at 12:26:14AM +0200, Javier Carrasco wrote:
>  >> >> syzbot has found an uninit-value bug triggered by the dm9601 driver [1].
>  >> >> 
>  >> >> This error happens because the variable res is not updated if the call
>  >> >> to dm_read_shared_word returns an error. In this particular case -EPROTO
>  >> >> was returned and res stayed uninitialized.
>  >> >> 
>  >> >> This can be avoided by checking the return value of dm_read_shared_word
>  >> >> and propagating the error if the read operation failed.
>  >> >> 
>  >> >> [1] https://syzkaller.appspot.com/bug?extid=1f53a30781af65d2c955
>  >> >> 
>  >> >> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx>
>  >> >> Reported-and-tested-by: syzbot+1f53a30781af65d2c955@xxxxxxxxxxxxxxxxxxxxxxxxx
>  >> >> ---
>  >> >> Changes in v2:
>  >> >> - Remove unnecessary 'err == 0' case
>  >> >> - Link to v1: https://lore.kernel.org/r/20231009-topic-dm9601_uninit_mdio_read-v1-1-d4d775e24e3b@xxxxxxxxx
>  >> >> ---
>  >> >> drivers/net/usb/dm9601.c | 7 ++++++-
>  >> >> 1 file changed, 6 insertions(+), 1 deletion(-)
>  >> 
>  >> > What commit id does this fix?
>  >> 
>  >> It has been there since the beginning, so:
>  >> 
>  >> Fixes: d0374f4f9c35cdfbee0 ("USB: Davicom DM9601 usbnet driver")
>  >> 
>  >> Acked-by: Peter Korsgaard <peter@xxxxxxxxxxxxx>
> 
>  > Great, can someone add a cc: stable@ tag for this too please?
> 
> Cc: stable@xxxxxxxxxxxxxxx

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>