CVE-2024-47707

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

ipv6: avoid possible NULL deref in rt6_uncached_list_flush_dev()

Blamed commit accidentally removed a check for rt->rt6i_idev being NULL,

as spotted by syzbot:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI

KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]

CPU: 1 UID: 0 PID: 10998 Comm: syz-executor Not tainted 6.11.0-rc6-syzkaller-00208-g625403177711 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024

RIP: 0010:rt6_uncached_list_flush_dev net/ipv6/route.c:177 [inline]

RIP: 0010:rt6_disable_ip+0x33e/0x7e0 net/ipv6/route.c:4914

Code: 41 80 3c 04 00 74 0a e8 90 d0 9b f7 48 8b 7c 24 08 48 8b 07 48 89 44 24 10 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 64 d0 9b f7 48 8b 44 24 18 49 39 06

RSP: 0018:ffffc900047374e0 EFLAGS: 00010246

RAX: 0000000000000000 RBX: 1ffff1100fdf8f33 RCX: dffffc0000000000

RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88807efc78c0

RBP: ffffc900047375d0 R08: 0000000000000003 R09: fffff520008e6e8c

R10: dffffc0000000000 R11: fffff520008e6e8c R12: 1ffff1100fdf8f18

R13: ffff88807efc7998 R14: 0000000000000000 R15: ffff88807efc7930

FS: 0000000000000000(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000000020002a80 CR3: 0000000022f62000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:

<TASK>

addrconf_ifdown+0x15d/0x1bd0 net/ipv6/addrconf.c:3856

addrconf_notify+0x3cb/0x1020

notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93

call_netdevice_notifiers_extack net/core/dev.c:2032 [inline]

call_netdevice_notifiers net/core/dev.c:2046 [inline]

unregister_netdevice_many_notify+0xd81/0x1c40 net/core/dev.c:11352

unregister_netdevice_many net/core/dev.c:11414 [inline]

unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11289

unregister_netdevice include/linux/netdevice.h:3129 [inline]

__tun_detach+0x6b9/0x1600 drivers/net/tun.c:685

tun_detach drivers/net/tun.c:701 [inline]

tun_chr_close+0x108/0x1b0 drivers/net/tun.c:3510

__fput+0x24a/0x8a0 fs/file_table.c:422

task_work_run+0x24f/0x310 kernel/task_work.c:228

exit_task_work include/linux/task_work.h:40 [inline]

do_exit+0xa2f/0x27f0 kernel/exit.c:882

do_group_exit+0x207/0x2c0 kernel/exit.c:1031

__do_sys_exit_group kernel/exit.c:1042 [inline]

__se_sys_exit_group kernel/exit.c:1040 [inline]

__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1040

x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232

do_syscall_x64 arch/x86/entry/common.c:52 [inline]

do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83

entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7f1acc77def9

Code: Unable to access opcode bytes at 0x7f1acc77decf.

RSP: 002b:00007ffeb26fa738 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7

RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1acc77def9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043

RBP: 00007f1acc7dd508 R08: 00007ffeb26f84d7 R09: 0000000000000003

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001

R13: 0000000000000003 R14: 00000000ffffffff R15: 00007ffeb26fa8e0

</TASK>

Modules linked in:

---[ end trace 0000000000000000 ]---

RIP: 0010:rt6_uncached_list_flush_dev net/ipv6/route.c:177 [inline]

RIP: 0010:rt6_disable_ip+0x33e/0x7e0 net/ipv6/route.c:4914

Code: 41 80 3c 04 00 74 0a e8 90 d0 9b f7 48 8b 7c 24 08 48 8b 07 48 89 44 24 10 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 64 d0 9b f7 48 8b 44 24 18 49 39 06

RSP: 0018:ffffc900047374e0 EFLAGS: 00010246

RAX: 0000000000000000 RBX: 1ffff1100fdf8f33 RCX: dffffc0000000000

RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88807efc78c0

R

---truncated---