Messages in this thread | | | Date | Fri, 06 Jun 2014 21:51:03 +0400 | From | Sergei Shtylyov <> | Subject | Re: net: llc: NULL ptr deref in llc_ui_sendmsg |
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Hello.
On 06/06/2014 07:42 PM, Dave Jones wrote:
> > Hi all,
> > While fuzzing with trinity inside a KVM tools guest running the latest -next > > kernel I've stumbled on the following spew:
> > [ 269.531162] BUG: unable to handle kernel NULL pointer dereference at 000000000000021e > > [ 269.531217] IP: llc_ui_sendmsg (net/llc/af_llc.c:912)
> 905 /* must bind connection to sap if user hasn't done it. */ > 906 if (sock_flag(sk, SOCK_ZAPPED)) { > 907 /* bind to sap with null dev, exclusive. */ > 908 rc = llc_ui_autobind(sock, addr); > 909 if (rc) > 910 goto release; > 911 } > 912 hdrlen = llc->dev->hard_header_len + llc_ui_header_len(sk, addr);
> looks like llc->dev was null, (understandable, given Trinity doesn't really know > how to set up llc beyond random socket()/setsockopt() calls).
> llc_ui_autobind returns -ENODEV in that case, so it looks like the SOCK_ZAPPED test > was false. Something like the patch below maybe ? It feels ugly to be duplicating that > test there, but if this is agreed upon I'll resubmit this properly.
> Dave
> diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c > index 0080d2b0a8ae..9b192db9883b 100644 > --- a/net/llc/af_llc.c > +++ b/net/llc/af_llc.c > @@ -908,6 +908,11 @@ static int llc_ui_sendmsg(struct kiocb *iocb, struct socket *sock, > rc = llc_ui_autobind(sock, addr); > if (rc) > goto release; > + } else { > + if (!llc->dev) {
} else if (!llc->dev) {
> + rc = -ENODEV; > + goto release; > + } > } > hdrlen = llc->dev->hard_header_len + llc_ui_header_len(sk, addr); > size = hdrlen + len;
WBR, Sergei
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