CVE: CVE-2024-47707
Published: 2024-10-21
Description: 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 0xdffffc[PII_REDACTED]: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x[PII_REDACTED]000000-0x[PII_REDACTED]000007]
CPU: 1 UID: 0 PID: 10998 Comm: syz-executor Not tainted 6.11.0-rc6-syzkaller-00208-g[PII_REDACTED]11 #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: [PII_REDACTED] RBX: 1ffff1100fdf8f33 RCX: dffffc[PII_REDACTED]
RDX: [PII_REDACTED] RSI: [PII_REDACTED] RDI: ffff88807efc78c0
RBP: ffffc900047375d0 R08: [PII_REDACTED] R09: fffff520008e6e8c
R10: dffffc[PII_REDACTED] R11: fffff520008e6e8c R12: 1ffff1100fdf8f18
R13: ffff88807efc7998 R14: [PII_REDACTED] R15: ffff88807efc7930
FS:  [PII_REDACTED](0000) GS:ffff8880b8900000(0000) knlGS:[PII_REDACTED]
CS:  0010 DS: 0000 ES: 0000 CR0: [PII_REDACTED]
CR2:[PII_REDACTED]002a80 CR3:[PII_REDACTED]f62000 CR4:[PII_REDACTED]3506f0
DR0: [PII_REDACTED] DR1: [PII_REDACTED] DR2: [PII_REDACTED]
DR3: [PII_REDACTED] DR6: 00000000fffe0ff0 DR7: [PII_REDACTED]
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:[PII_REDACTED]0000e7
RAX: ffffffffffffffda RBX: [PII_REDACTED] RCX: 00007f1acc77def9
RDX: [PII_REDACTED] RSI: [PII_REDACTED] RDI: [PII_REDACTED]
RBP: 00007f1acc7dd508 R08: 00007ffeb26f84d7 R09: [PII_REDACTED]
R10: [PII_REDACTED] R11: [PII_REDACTED] R12: [PII_REDACTED]
R13: [PII_REDACTED] R14: 00000000ffffffff R15: 00007ffeb26fa8e0
 </TASK>
Modules linked in:
---[ end trace [PII_REDACTED] ]---
 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: [PII_REDACTED] RBX: 1ffff1100fdf8f33 RCX: dffffc[PII_REDACTED]
RDX: [PII_REDACTED] RSI: [PII_REDACTED] RDI: ffff88807efc78c0
R
---truncated---
CVSS Score: 5.5 (MEDIUM)
CWE: CWE-476
References: https://git.kernel.org/stable/c/04ccecfa959d3b9ae7348780d8e379c6486176ac; https://git.kernel.org/stable/c/08409e401622e2896b4313be9f781bde8a2a6a53; https://git.kernel.org/stable/c/0ceb2f2b5c813f932d6e60d3feec5e7e713da783