Re: [PATCH 090/173] USB: serial/kobil_sct, fix potential tty NULL dereference

[Willy Tarreau]

On Tue, Apr 26, 2011 at 12:07:07PM +0200, Jiri Slaby wrote:
> On 04/25/2011 10:04 PM, Willy Tarreau wrote:
> >2.6.27.59-stable review patch.  If anyone has any objections, please let 
> >us know.
> >
> >------------------
> >
> >From: Jiri Slaby<jslaby@xxxxxxx>
> >
> >commit 6960f40a954619857e7095a6179eef896f297077 upstream.
> >
> >Make sure that we check the return value of tty_port_tty_get.
> >Sometimes it may return NULL and we later dereference that.
> >
> >The only place here is in kobil_read_int_callback, so fix it.
> >
> >Signed-off-by: Jiri Slaby<jslaby@xxxxxxx>
> >Cc: Alan Cox<alan@xxxxxxxxxxxxxxx>
> >Signed-off-by: Greg Kroah-Hartman<gregkh@xxxxxxx>
> >
> >---
> >  drivers/usb/serial/kobil_sct.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >--- a/drivers/usb/serial/kobil_sct.c
> >+++ b/drivers/usb/serial/kobil_sct.c
> >@@ -372,7 +372,7 @@ static void kobil_read_int_callback(stru
> >  	}
> >
> >  	tty = port->port.tty;
> >-	if (urb->actual_length) {
> >+	if (tty&&  urb->actual_length) {
> 
> Ok, but this doesn't fix the bug (the URB should be killed or something 
> similar in that kernel), it only makes the window smaller.

OK I get it now, it requires patch 4a90f09b which is quite not some
suitable material for -longterm.

Do you think it's better to completely remove this patch than making
one think the risk of bug is gone while it is not ? Unless we find
something more reliable, I'd rather drop the patch.

Thanks,
Willy

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