CVE-2026-23095

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> gue: Fix skb memleak with inner IP protocol 0.<br /> <br /> syzbot reported skb memleak below. [0]<br /> <br /> The repro generated a GUE packet with its inner protocol 0.<br /> <br /> gue_udp_recv() returns -guehdr-&gt;proto_ctype for "resubmit"<br /> in ip_protocol_deliver_rcu(), but this only works with<br /> non-zero protocol number.<br /> <br /> Let&amp;#39;s drop such packets.<br /> <br /> Note that 0 is a valid number (IPv6 Hop-by-Hop Option).<br /> <br /> I think it is not practical to encap HOPOPT in GUE, so once<br /> someone starts to complain, we could pass down a resubmit<br /> flag pointer to distinguish two zeros from the upper layer:<br /> <br /> * no error<br /> * resubmit HOPOPT<br /> <br /> [0]<br /> BUG: memory leak<br /> unreferenced object 0xffff888109695a00 (size 240):<br /> comm "syz.0.17", pid 6088, jiffies 4294943096<br /> hex dump (first 32 bytes):<br /> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................<br /> 00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00 .@..............<br /> backtrace (crc a84b336f):<br /> kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]<br /> slab_post_alloc_hook mm/slub.c:4958 [inline]<br /> slab_alloc_node mm/slub.c:5263 [inline]<br /> kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270<br /> __build_skb+0x23/0x60 net/core/skbuff.c:474<br /> build_skb+0x20/0x190 net/core/skbuff.c:490<br /> __tun_build_skb drivers/net/tun.c:1541 [inline]<br /> tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636<br /> tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770<br /> tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999<br /> new_sync_write fs/read_write.c:593 [inline]<br /> vfs_write+0x45d/0x710 fs/read_write.c:686<br /> ksys_write+0xa7/0x170 fs/read_write.c:738<br /> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]<br /> do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f