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Message-ID: <20240820160859.3786976-2-edumazet@google.com>
Date: Tue, 20 Aug 2024 16:08:57 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>, syzbot <syzkaller@...glegroups.com>
Subject: [PATCH v2 net 1/3] ipv6: prevent UAF in ip6_send_skb()
syzbot reported an UAF in ip6_send_skb() [1]
After ip6_local_out() has returned, we no longer can safely
dereference rt, unless we hold rcu_read_lock().
A similar issue has been fixed in commit
a688caa34beb ("ipv6: take rcu lock in rawv6_send_hdrinc()")
Another potential issue in ip6_finish_output2() is handled in a
separate patch.
[1]
BUG: KASAN: slab-use-after-free in ip6_send_skb+0x18d/0x230 net/ipv6/ip6_output.c:1964
Read of size 8 at addr ffff88806dde4858 by task syz.1.380/6530
CPU: 1 UID: 0 PID: 6530 Comm: syz.1.380 Not tainted 6.11.0-rc3-syzkaller-00306-gdf6cbc62cc9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:93 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
ip6_send_skb+0x18d/0x230 net/ipv6/ip6_output.c:1964
rawv6_push_pending_frames+0x75c/0x9e0 net/ipv6/raw.c:588
rawv6_sendmsg+0x19c7/0x23c0 net/ipv6/raw.c:926
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x1a6/0x270 net/socket.c:745
sock_write_iter+0x2dd/0x400 net/socket.c:1160
do_iter_readv_writev+0x60a/0x890
vfs_writev+0x37c/0xbb0 fs/read_write.c:971
do_writev+0x1b1/0x350 fs/read_write.c:1018
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: 0033:0x7f936bf79e79
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:00007f936cd7f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f936c115f80 RCX: 00007f936bf79e79
RDX: 0000000000000001 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00007f936bfe7916 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f936c115f80 R15: 00007fff2860a7a8
</TASK>
Allocated by task 6530:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:312 [inline]
__kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3988 [inline]
slab_alloc_node mm/slub.c:4037 [inline]
kmem_cache_alloc_noprof+0x135/0x2a0 mm/slub.c:4044
dst_alloc+0x12b/0x190 net/core/dst.c:89
ip6_blackhole_route+0x59/0x340 net/ipv6/route.c:2670
make_blackhole net/xfrm/xfrm_policy.c:3120 [inline]
xfrm_lookup_route+0xd1/0x1c0 net/xfrm/xfrm_policy.c:3313
ip6_dst_lookup_flow+0x13e/0x180 net/ipv6/ip6_output.c:1257
rawv6_sendmsg+0x1283/0x23c0 net/ipv6/raw.c:898
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x1a6/0x270 net/socket.c:745
____sys_sendmsg+0x525/0x7d0 net/socket.c:2597
___sys_sendmsg net/socket.c:2651 [inline]
__sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680
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
Freed by task 45:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2252 [inline]
slab_free mm/slub.c:4473 [inline]
kmem_cache_free+0x145/0x350 mm/slub.c:4548
dst_destroy+0x2ac/0x460 net/core/dst.c:124
rcu_do_batch kernel/rcu/tree.c:2569 [inline]
rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2843
handle_softirqs+0x2c4/0x970 kernel/softirq.c:554
__do_softirq kernel/softirq.c:588 [inline]
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
Last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
__call_rcu_common kernel/rcu/tree.c:3106 [inline]
call_rcu+0x167/0xa70 kernel/rcu/tree.c:3210
refdst_drop include/net/dst.h:263 [inline]
skb_dst_drop include/net/dst.h:275 [inline]
nf_ct_frag6_queue net/ipv6/netfilter/nf_conntrack_reasm.c:306 [inline]
nf_ct_frag6_gather+0xb9a/0x2080 net/ipv6/netfilter/nf_conntrack_reasm.c:485
ipv6_defrag+0x2c8/0x3c0 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:67
nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
nf_hook_slow+0xc3/0x220 net/netfilter/core.c:626
nf_hook include/linux/netfilter.h:269 [inline]
__ip6_local_out+0x6fa/0x800 net/ipv6/output_core.c:143
ip6_local_out+0x26/0x70 net/ipv6/output_core.c:153
ip6_send_skb+0x112/0x230 net/ipv6/ip6_output.c:1959
rawv6_push_pending_frames+0x75c/0x9e0 net/ipv6/raw.c:588
rawv6_sendmsg+0x19c7/0x23c0 net/ipv6/raw.c:926
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x1a6/0x270 net/socket.c:745
sock_write_iter+0x2dd/0x400 net/socket.c:1160
do_iter_readv_writev+0x60a/0x890
Fixes: 0625491493d9 ("ipv6: ip6_push_pending_frames() should increment IPSTATS_MIB_OUTDISCARDS")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
---
net/ipv6/ip6_output.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ab504d31f0cdd8dec9ab01bf9d6e6517307609cd..f7b53effc80f8b3b7a839f58097d021a11f9eb37 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1956,6 +1956,7 @@ int ip6_send_skb(struct sk_buff *skb)
struct rt6_info *rt = dst_rt6_info(skb_dst(skb));
int err;
+ rcu_read_lock();
err = ip6_local_out(net, skb->sk, skb);
if (err) {
if (err > 0)
@@ -1965,6 +1966,7 @@ int ip6_send_skb(struct sk_buff *skb)
IPSTATS_MIB_OUTDISCARDS);
}
+ rcu_read_unlock();
return err;
}
--
2.46.0.184.g6999bdac58-goog
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