CVE-2026-53111

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> bpf: test_run: Fix the null pointer dereference issue in bpf_lwt_xmit_push_encap<br /> <br /> The bpf_lwt_xmit_push_encap helper needs to access skb_dst(skb)-&gt;dev to<br /> calculate the needed headroom:<br /> <br /> err = skb_cow_head(skb,<br /> len + LL_RESERVED_SPACE(skb_dst(skb)-&gt;dev));<br /> <br /> But skb-&gt;_skb_refdst may not be initialized when the skb is set up by<br /> bpf_prog_test_run_skb function. Executing bpf_lwt_push_ip_encap function<br /> in this scenario will trigger null pointer dereference, causing a kernel<br /> crash as Yinhao reported:<br /> <br /> [ 105.186365] BUG: kernel NULL pointer dereference, address: 0000000000000000<br /> [ 105.186382] #PF: supervisor read access in kernel mode<br /> [ 105.186388] #PF: error_code(0x0000) - not-present page<br /> [ 105.186393] PGD 121d3d067 P4D 121d3d067 PUD 106c83067 PMD 0<br /> [ 105.186404] Oops: 0000 [#1] PREEMPT SMP NOPTI<br /> [ 105.186412] CPU: 3 PID: 3250 Comm: poc Kdump: loaded Not tainted 6.19.0-rc5 #1<br /> [ 105.186423] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014<br /> [ 105.186427] RIP: 0010:bpf_lwt_push_ip_encap+0x1eb/0x520<br /> [ 105.186443] Code: 0f 84 de 01 00 00 0f b7 4a 04 66 85 c9 0f 85 47 01 00 00 31 c0 5b 5d 41 5c 41 5d 41 5e c3 cc cc cc cc 48 8b 73 58 48 83 e6 fe 8b 36 0f b7 be ec 00 00 00 0f b7 b6 e6 00 00 00 01 fe 83 e6 f0<br /> [ 105.186449] RSP: 0018:ffffbb0e0387bc50 EFLAGS: 00010246<br /> [ 105.186455] RAX: 000000000000004e RBX: ffff94c74e036500 RCX: ffff94c74874da00<br /> [ 105.186460] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff94c74e036500<br /> [ 105.186463] RBP: 0000000000000001 R08: 0000000000000002 R09: 0000000000000000<br /> [ 105.186467] R10: ffffbb0e0387bd50 R11: 0000000000000000 R12: ffffbb0e0387bc98<br /> [ 105.186471] R13: 0000000000000014 R14: 0000000000000000 R15: 0000000000000002<br /> [ 105.186484] FS: 00007f166aa4d680(0000) GS:ffff94c8b7780000(0000) knlGS:0000000000000000<br /> [ 105.186490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> [ 105.186494] CR2: 0000000000000000 CR3: 000000015eade001 CR4: 0000000000770ee0<br /> [ 105.186499] PKRU: 55555554<br /> [ 105.186502] Call Trace:<br /> [ 105.186507] <br /> [ 105.186513] bpf_lwt_xmit_push_encap+0x2b/0x40<br /> [ 105.186522] bpf_prog_a75eaad51e517912+0x41/0x49<br /> [ 105.186536] ? kvm_clock_get_cycles+0x18/0x30<br /> [ 105.186547] ? ktime_get+0x3c/0xa0<br /> [ 105.186554] bpf_test_run+0x195/0x320<br /> [ 105.186563] ? bpf_test_run+0x10f/0x320<br /> [ 105.186579] bpf_prog_test_run_skb+0x2f5/0x4f0<br /> [ 105.186590] __sys_bpf+0x69c/0xa40<br /> [ 105.186603] __x64_sys_bpf+0x1e/0x30<br /> [ 105.186611] do_syscall_64+0x59/0x110<br /> [ 105.186620] entry_SYSCALL_64_after_hwframe+0x76/0xe0<br /> [ 105.186649] RIP: 0033:0x7f166a97455d<br /> <br /> Temporarily add the setting of skb-&gt;_skb_refdst before bpf_test_run to resolve the issue.