* [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del().
@ 2026-01-13 1:05 Kuniyuki Iwashima
2026-01-13 4:35 ` Hangbin Liu
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Kuniyuki Iwashima @ 2026-01-13 1:05 UTC (permalink / raw)
To: David S. Miller, David Ahern, Eric Dumazet, Jakub Kicinski,
Paolo Abeni
Cc: Simon Horman, Hangbin Liu, Kuniyuki Iwashima, Kuniyuki Iwashima,
netdev, syzbot+72e610f4f1a930ca9d8a
syzbot reported use-after-free of inet6_ifaddr in
inet6_addr_del(). [0]
The cited commit accidentally moved ipv6_del_addr() for
mngtmpaddr before reading its ifp->flags for temporary
addresses in inet6_addr_del().
Let's move ipv6_del_addr() down to fix the UAF.
[0]:
BUG: KASAN: slab-use-after-free in inet6_addr_del.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>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcd/0x630 mm/kasan/report.c:482
kasan_report+0xe0/0x110 mm/kasan/report.c:595
inet6_addr_del.constprop.0+0x67a/0x6b0 net/ipv6/addrconf.c:3117
addrconf_del_ifaddr+0x11e/0x190 net/ipv6/addrconf.c:3181
inet6_ioctl+0x1e5/0x2b0 net/ipv6/af_inet6.c:582
sock_do_ioctl+0x118/0x280 net/socket.c:1254
sock_ioctl+0x227/0x6b0 net/socket.c:1375
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+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 ORIG_RAX: 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:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
kasan_save_track+0x14/0x30 mm/kasan/common.c:77
poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:414
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
ipv6_add_addr+0x4e3/0x2010 net/ipv6/addrconf.c:1120
inet6_addr_add+0x256/0x9b0 net/ipv6/addrconf.c:3050
addrconf_add_ifaddr+0x1fc/0x450 net/ipv6/addrconf.c:3160
inet6_ioctl+0x103/0x2b0 net/ipv6/af_inet6.c:580
sock_do_ioctl+0x118/0x280 net/socket.c:1254
sock_ioctl+0x227/0x6b0 net/socket.c:1375
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6099:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
kasan_save_track+0x14/0x30 mm/kasan/common.c:77
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free_freelist_hook mm/slub.c:2569 [inline]
slab_free_bulk mm/slub.c:6696 [inline]
kmem_cache_free_bulk mm/slub.c:7383 [inline]
kmem_cache_free_bulk+0x2bf/0x680 mm/slub.c:7362
kfree_bulk include/linux/slab.h:830 [inline]
kvfree_rcu_bulk+0x1b7/0x1e0 mm/slab_common.c:1523
kvfree_rcu_drain_ready mm/slab_common.c:1728 [inline]
kfree_rcu_monitor+0x1d0/0x2f0 mm/slab_common.c:1801
process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
process_scheduled_works kernel/workqueue.c:3340 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Fixes: 00b5b7aab9e42 ("net/ipv6: delete temporary address if mngtmpaddr is removed or unmanaged")
Reported-by: syzbot+72e610f4f1a930ca9d8a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/696598e9.050a0220.3be5c5.0009.GAE@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
net/ipv6/addrconf.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index b66217d1b2f82..27ab9d7adc649 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3112,12 +3112,12 @@ static int inet6_addr_del(struct net *net, int ifindex, u32 ifa_flags,
in6_ifa_hold(ifp);
read_unlock_bh(&idev->lock);
- ipv6_del_addr(ifp);
-
if (!(ifp->flags & IFA_F_TEMPORARY) &&
(ifp->flags & IFA_F_MANAGETEMPADDR))
delete_tempaddrs(idev, ifp);
+ ipv6_del_addr(ifp);
+
addrconf_verify_rtnl(net);
if (ipv6_addr_is_multicast(pfx)) {
ipv6_mc_config(net->ipv6.mc_autojoin_sk,
--
2.52.0.457.g6b5491de43-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del().
2026-01-13 1:05 [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del() Kuniyuki Iwashima
@ 2026-01-13 4:35 ` Hangbin Liu
2026-01-13 8:47 ` Eric Dumazet
2026-01-14 3:10 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Hangbin Liu @ 2026-01-13 4:35 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: David S. Miller, David Ahern, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Simon Horman, Kuniyuki Iwashima, netdev,
syzbot+72e610f4f1a930ca9d8a
On Tue, Jan 13, 2026 at 01:05:08AM +0000, Kuniyuki Iwashima wrote:
> syzbot reported use-after-free of inet6_ifaddr in
> inet6_addr_del(). [0]
>
> The cited commit accidentally moved ipv6_del_addr() for
> mngtmpaddr before reading its ifp->flags for temporary
> addresses in inet6_addr_del().
>
> Let's move ipv6_del_addr() down to fix the UAF.
>
> [0]:
> BUG: KASAN: slab-use-after-free in inet6_addr_del.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>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
> print_address_description mm/kasan/report.c:378 [inline]
> print_report+0xcd/0x630 mm/kasan/report.c:482
> kasan_report+0xe0/0x110 mm/kasan/report.c:595
> inet6_addr_del.constprop.0+0x67a/0x6b0 net/ipv6/addrconf.c:3117
> addrconf_del_ifaddr+0x11e/0x190 net/ipv6/addrconf.c:3181
> inet6_ioctl+0x1e5/0x2b0 net/ipv6/af_inet6.c:582
> sock_do_ioctl+0x118/0x280 net/socket.c:1254
> sock_ioctl+0x227/0x6b0 net/socket.c:1375
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:597 [inline]
> __se_sys_ioctl fs/ioctl.c:583 [inline]
> __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+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 ORIG_RAX: 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:
> kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
> kasan_save_track+0x14/0x30 mm/kasan/common.c:77
> poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
> __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:414
> kmalloc_noprof include/linux/slab.h:957 [inline]
> kzalloc_noprof include/linux/slab.h:1094 [inline]
> ipv6_add_addr+0x4e3/0x2010 net/ipv6/addrconf.c:1120
> inet6_addr_add+0x256/0x9b0 net/ipv6/addrconf.c:3050
> addrconf_add_ifaddr+0x1fc/0x450 net/ipv6/addrconf.c:3160
> inet6_ioctl+0x103/0x2b0 net/ipv6/af_inet6.c:580
> sock_do_ioctl+0x118/0x280 net/socket.c:1254
> sock_ioctl+0x227/0x6b0 net/socket.c:1375
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:597 [inline]
> __se_sys_ioctl fs/ioctl.c:583 [inline]
> __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Freed by task 6099:
> kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
> kasan_save_track+0x14/0x30 mm/kasan/common.c:77
> kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584
> poison_slab_object mm/kasan/common.c:252 [inline]
> __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
> kasan_slab_free include/linux/kasan.h:234 [inline]
> slab_free_hook mm/slub.c:2540 [inline]
> slab_free_freelist_hook mm/slub.c:2569 [inline]
> slab_free_bulk mm/slub.c:6696 [inline]
> kmem_cache_free_bulk mm/slub.c:7383 [inline]
> kmem_cache_free_bulk+0x2bf/0x680 mm/slub.c:7362
> kfree_bulk include/linux/slab.h:830 [inline]
> kvfree_rcu_bulk+0x1b7/0x1e0 mm/slab_common.c:1523
> kvfree_rcu_drain_ready mm/slab_common.c:1728 [inline]
> kfree_rcu_monitor+0x1d0/0x2f0 mm/slab_common.c:1801
> process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
> process_scheduled_works kernel/workqueue.c:3340 [inline]
> worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
> kthread+0x3c5/0x780 kernel/kthread.c:463
> ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
>
> Fixes: 00b5b7aab9e42 ("net/ipv6: delete temporary address if mngtmpaddr is removed or unmanaged")
> Reported-by: syzbot+72e610f4f1a930ca9d8a@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/696598e9.050a0220.3be5c5.0009.GAE@google.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> ---
> net/ipv6/addrconf.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index b66217d1b2f82..27ab9d7adc649 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -3112,12 +3112,12 @@ static int inet6_addr_del(struct net *net, int ifindex, u32 ifa_flags,
> in6_ifa_hold(ifp);
> read_unlock_bh(&idev->lock);
>
> - ipv6_del_addr(ifp);
> -
> if (!(ifp->flags & IFA_F_TEMPORARY) &&
> (ifp->flags & IFA_F_MANAGETEMPADDR))
> delete_tempaddrs(idev, ifp);
>
> + ipv6_del_addr(ifp);
> +
> addrconf_verify_rtnl(net);
> if (ipv6_addr_is_multicast(pfx)) {
> ipv6_mc_config(net->ipv6.mc_autojoin_sk,
> --
> 2.52.0.457.g6b5491de43-goog
>
Hmm, I'm unable to recall why I moved delete_tempaddrs() after
ipv6_del_addr(). But your patch make sense to me. Checking the ifp flags
before ipv6_del_addr(ifp) is safer.
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del().
2026-01-13 1:05 [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del() Kuniyuki Iwashima
2026-01-13 4:35 ` Hangbin Liu
@ 2026-01-13 8:47 ` Eric Dumazet
2026-01-14 3:10 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2026-01-13 8:47 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: David S. Miller, David Ahern, Jakub Kicinski, Paolo Abeni,
Simon Horman, Hangbin Liu, Kuniyuki Iwashima, netdev,
syzbot+72e610f4f1a930ca9d8a
On Tue, Jan 13, 2026 at 2:05 AM Kuniyuki Iwashima <kuniyu@google.com> wrote:
>
> syzbot reported use-after-free of inet6_ifaddr in
> inet6_addr_del(). [0]
>
> The cited commit accidentally moved ipv6_del_addr() for
> mngtmpaddr before reading its ifp->flags for temporary
> addresses in inet6_addr_del().
>
> Let's move ipv6_del_addr() down to fix the UAF.
>
> Fixes: 00b5b7aab9e42 ("net/ipv6: delete temporary address if mngtmpaddr is removed or unmanaged")
> Reported-by: syzbot+72e610f4f1a930ca9d8a@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/696598e9.050a0220.3be5c5.0009.GAE@google.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> ---
Reviewed-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del().
2026-01-13 1:05 [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del() Kuniyuki Iwashima
2026-01-13 4:35 ` Hangbin Liu
2026-01-13 8:47 ` Eric Dumazet
@ 2026-01-14 3:10 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2026-01-14 3:10 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: davem, dsahern, edumazet, kuba, pabeni, horms, liuhangbin,
kuni1840, netdev, syzbot+72e610f4f1a930ca9d8a
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Tue, 13 Jan 2026 01:05:08 +0000 you wrote:
> syzbot reported use-after-free of inet6_ifaddr in
> inet6_addr_del(). [0]
>
> The cited commit accidentally moved ipv6_del_addr() for
> mngtmpaddr before reading its ifp->flags for temporary
> addresses in inet6_addr_del().
>
> [...]
Here is the summary with links:
- [v1,net] ipv6: Fix use-after-free in inet6_addr_del().
https://git.kernel.org/netdev/net/c/ddf96c393a33
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-01-14 3:13 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2026-01-13 1:05 [PATCH v1 net] ipv6: Fix use-after-free in inet6_addr_del() Kuniyuki Iwashima
2026-01-13 4:35 ` Hangbin Liu
2026-01-13 8:47 ` Eric Dumazet
2026-01-14 3:10 ` patchwork-bot+netdevbpf
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