CVE-2026-31422

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/sched: cls_flow: fix NULL pointer dereference on shared blocks<br /> <br /> flow_change() calls tcf_block_q() and dereferences q-&gt;handle to derive<br /> a default baseclass. Shared blocks leave block-&gt;q NULL, causing a NULL<br /> deref when a flow filter without a fully qualified baseclass is created<br /> on a shared block.<br /> <br /> Check tcf_block_shared() before accessing block-&gt;q and return -EINVAL<br /> for shared blocks. This avoids the null-deref shown below:<br /> <br /> =======================================================================<br /> KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]<br /> RIP: 0010:flow_change (net/sched/cls_flow.c:508)<br /> Call Trace:<br /> tc_new_tfilter (net/sched/cls_api.c:2432)<br /> rtnetlink_rcv_msg (net/core/rtnetlink.c:6980)<br /> [...]<br /> =======================================================================