CVE-2026-53069

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net, bpf: fix null-ptr-deref in xdp_master_redirect() for down master<br /> <br /> syzkaller reported a kernel panic in bond_rr_gen_slave_id() reached via<br /> xdp_master_redirect(). Full decoded trace:<br /> <br /> https://syzkaller.appspot.com/bug?extid=80e046b8da2820b6ba73<br /> <br /> bond_rr_gen_slave_id() dereferences bond-&gt;rr_tx_counter, a per-CPU<br /> counter that bonding only allocates in bond_open() when the mode is<br /> round-robin. If the bond device was never brought up, rr_tx_counter<br /> stays NULL.<br /> <br /> The XDP redirect path can still reach that code on a bond that was<br /> never opened: bpf_master_redirect_enabled_key is a global static key,<br /> so as soon as any bond device has native XDP attached, the<br /> XDP_TX -&gt; xdp_master_redirect() interception is enabled for every<br /> slave system-wide. The path xdp_master_redirect() -&gt;<br /> bond_xdp_get_xmit_slave() -&gt; bond_xdp_xmit_roundrobin_slave_get() -&gt;<br /> bond_rr_gen_slave_id() then runs against a bond that has no<br /> rr_tx_counter and crashes.<br /> <br /> Fix this in the generic xdp_master_redirect() by refusing to call into<br /> the master&amp;#39;s -&gt;ndo_xdp_get_xmit_slave() when the master device is not<br /> up. IFF_UP is only set after -&gt;ndo_open() has successfully returned,<br /> so this reliably excludes masters whose XDP state has not been fully<br /> initialized. Drop the frame with XDP_ABORTED so the exception is<br /> visible via trace_xdp_exception() rather than silently falling through.<br /> This is not specific to bonding: any current or future master that<br /> defers XDP state allocation to -&gt;ndo_open() is protected.