CVE-2026-23010: ipv6: Fix use-after-free in inet6_addr_del().

In the Linux kernel, the following vulnerability has been resolved:

ipv6: Fix use-after-free in inet6addrdel().

syzbot reported use-after-free of inet6ifaddr in inet6addrdel(). [0]

The cited commit accidentally moved ipv6deladdr() for mngtmpaddr before reading its ifp->flags for temporary addresses in inet6addrdel().

Let's move ipv6deladdr() down to fix the UAF.

[0]: BUG: KASAN: slab-use-after-free in inet6addrdel.constprop.0+0x67a/0x6b0 net/ipv6/addrconf.c:3117 Read of size 4 at addr ffff88807b89c86c by task syz.3.1618/9593

CPU: 0 UID: 0 PID: 9593 Comm: syz.3.1618 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: <TASK> dumpstack lib/dumpstack.c:94 [inline] dumpstacklvl+0x116/0x1f0 lib/dumpstack.c:120 printaddressdescription mm/kasan/report.c:378 [inline] printreport+0xcd/0x630 mm/kasan/report.c:482 kasanreport+0xe0/0x110 mm/kasan/report.c:595 inet6addrdel.constprop.0+0x67a/0x6b0 net/ipv6/addrconf.c:3117 addrconfdelifaddr+0x11e/0x190 net/ipv6/addrconf.c:3181 inet6ioctl+0x1e5/0x2b0 net/ipv6/afinet6.c:582 sockdoioctl+0x118/0x280 net/socket.c:1254 sockioctl+0x227/0x6b0 net/socket.c:1375 vfsioctl fs/ioctl.c:51 [inline] dosysioctl fs/ioctl.c:597 [inline] sesysioctl fs/ioctl.c:583 [inline] x64sysioctl+0x18e/0x210 fs/ioctl.c:583 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0xcd/0xf80 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x77/0x7f RIP: 0033:0x7f164cf8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f164de64038 EFLAGS: 00000246 ORIGRAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f164d1e5fa0 RCX: 00007f164cf8f749 RDX: 0000200000000000 RSI: 0000000000008936 RDI: 0000000000000003 RBP: 00007f164d013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f164d1e6038 R14: 00007f164d1e5fa0 R15: 00007ffde15c8288 </TASK>

Allocated by task 9593: kasansavestack+0x33/0x60 mm/kasan/common.c:56 kasansavetrack+0x14/0x30 mm/kasan/common.c:77 poisonkmallocredzone mm/kasan/common.c:397 [inline] kasankmalloc+0xaa/0xb0 mm/kasan/common.c:414 kmallocnoprof include/linux/slab.h:957 [inline] kzallocnoprof include/linux/slab.h:1094 [inline] ipv6addaddr+0x4e3/0x2010 net/ipv6/addrconf.c:1120 inet6addradd+0x256/0x9b0 net/ipv6/addrconf.c:3050 addrconfaddifaddr+0x1fc/0x450 net/ipv6/addrconf.c:3160 inet6ioctl+0x103/0x2b0 net/ipv6/afinet6.c:580 sockdoioctl+0x118/0x280 net/socket.c:1254 sockioctl+0x227/0x6b0 net/socket.c:1375 vfsioctl fs/ioctl.c:51 [inline] dosysioctl fs/ioctl.c:597 [inline] sesysioctl fs/ioctl.c:583 [inline] x64sysioctl+0x18e/0x210 fs/ioctl.c:583 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0xcd/0xf80 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x77/0x7f

Freed by task 6099: kasansavestack+0x33/0x60 mm/kasan/common.c:56 kasansavetrack+0x14/0x30 mm/kasan/common.c:77 kasansavefreeinfo+0x3b/0x60 mm/kasan/generic.c:584 poisonslabobject mm/kasan/common.c:252 [inline] kasanslabfree+0x5f/0x80 mm/kasan/common.c:284 kasanslabfree include/linux/kasan.h:234 [inline] slabfreehook mm/slub.c:2540 [inline] slabfreefreelisthook mm/slub.c:2569 [inline] slabfreebulk mm/slub.c:6696 [inline] kmemcachefreebulk mm/slub.c:7383 [inline] kmemcachefreebulk+0x2bf/0x680 mm/slub.c:7362 kfreebulk include/linux/slab.h:830 [inline] kvfreercubulk+0x1b7/0x1e0 mm/slabcommon.c:1523 kvfreercudrainready mm/slabcommon.c:1728 [inline] kfreercumonitor+0x1d0/0x2f0 mm/slabcommon.c:1801 processonework+0x9ba/0x1b20 kernel/workqueue.c:3257 processscheduledworks kernel/workqu ---truncated---