* [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close().
@ 2025-07-02 1:43 Kuniyuki Iwashima
2025-07-02 6:34 ` Tung Quang Nguyen
2025-07-08 2:00 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Kuniyuki Iwashima @ 2025-07-02 1:43 UTC (permalink / raw)
To: Jon Maloy, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni
Cc: Simon Horman, Ying Xue, Kuniyuki Iwashima, Kuniyuki Iwashima,
netdev, tipc-discussion, syzbot+d333febcf8f4bc5f6110
syzbot reported a null-ptr-deref in tipc_conn_close() during netns
dismantle. [0]
tipc_topsrv_stop() iterates tipc_net(net)->topsrv->conn_idr and calls
tipc_conn_close() for each tipc_conn.
The problem is that tipc_conn_close() is called after releasing the
IDR lock.
At the same time, there might be tipc_conn_recv_work() running and it
could call tipc_conn_close() for the same tipc_conn and release its
last ->kref.
Once we release the IDR lock in tipc_topsrv_stop(), there is no
guarantee that the tipc_conn is alive.
Let's hold the ref before releasing the lock and put the ref after
tipc_conn_close() in tipc_topsrv_stop().
[0]:
BUG: KASAN: use-after-free in tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165
Read of size 8 at addr ffff888099305a08 by task kworker/u4:3/435
CPU: 0 PID: 435 Comm: kworker/u4:3 Not tainted 4.19.204-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165
tipc_topsrv_stop net/tipc/topsrv.c:701 [inline]
tipc_topsrv_exit_net+0x27b/0x5c0 net/tipc/topsrv.c:722
ops_exit_list+0xa5/0x150 net/core/net_namespace.c:153
cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Allocated by task 23:
kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
tipc_conn_alloc+0x43/0x4f0 net/tipc/topsrv.c:192
tipc_topsrv_accept+0x1b5/0x280 net/tipc/topsrv.c:470
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Freed by task 23:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
tipc_conn_kref_release net/tipc/topsrv.c:150 [inline]
kref_put include/linux/kref.h:70 [inline]
conn_put+0x2cd/0x3a0 net/tipc/topsrv.c:155
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
The buggy address belongs to the object at ffff888099305a00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
512-byte region [ffff888099305a00, ffff888099305c00)
The buggy address belongs to the page:
page:ffffea000264c140 count:1 mapcount:0 mapping:ffff88813bff0940 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00028b6b88 ffffea0002cd2b08 ffff88813bff0940
raw: 0000000000000000 ffff888099305000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888099305900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888099305980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888099305a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888099305a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888099305b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Fixes: c5fa7b3cf3cb ("tipc: introduce new TIPC server infrastructure")
Reported-by: syzbot+d333febcf8f4bc5f6110@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=27169a847a70550d17be
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
net/tipc/topsrv.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c
index 8ee0c07d00e9..ffe577bf6b51 100644
--- a/net/tipc/topsrv.c
+++ b/net/tipc/topsrv.c
@@ -704,8 +704,10 @@ static void tipc_topsrv_stop(struct net *net)
for (id = 0; srv->idr_in_use; id++) {
con = idr_find(&srv->conn_idr, id);
if (con) {
+ conn_get(con);
spin_unlock_bh(&srv->idr_lock);
tipc_conn_close(con);
+ conn_put(con);
spin_lock_bh(&srv->idr_lock);
}
}
--
2.50.0.727.gbf7dc18ff4-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* RE: [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close().
2025-07-02 1:43 [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close() Kuniyuki Iwashima
@ 2025-07-02 6:34 ` Tung Quang Nguyen
2025-07-08 2:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Tung Quang Nguyen @ 2025-07-02 6:34 UTC (permalink / raw)
To: Kuniyuki Iwashima, Jon Maloy, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni
Cc: Simon Horman, Ying Xue, Kuniyuki Iwashima, netdev@vger.kernel.org,
tipc-discussion@lists.sourceforge.net,
syzbot+d333febcf8f4bc5f6110@syzkaller.appspotmail.com
>Subject: [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close().
>
>syzbot reported a null-ptr-deref in tipc_conn_close() during netns dismantle.
>[0]
>
>tipc_topsrv_stop() iterates tipc_net(net)->topsrv->conn_idr and calls
>tipc_conn_close() for each tipc_conn.
>
>The problem is that tipc_conn_close() is called after releasing the IDR lock.
>
>At the same time, there might be tipc_conn_recv_work() running and it could
>call tipc_conn_close() for the same tipc_conn and release its last ->kref.
>
>Once we release the IDR lock in tipc_topsrv_stop(), there is no guarantee that
>the tipc_conn is alive.
>
>Let's hold the ref before releasing the lock and put the ref after
>tipc_conn_close() in tipc_topsrv_stop().
>
>[0]:
>BUG: KASAN: use-after-free in tipc_conn_close+0x122/0x140
>net/tipc/topsrv.c:165 Read of size 8 at addr ffff888099305a08 by task
>kworker/u4:3/435
>
>CPU: 0 PID: 435 Comm: kworker/u4:3 Not tainted 4.19.204-syzkaller #0
>Hardware name: Google Google Compute Engine/Google Compute Engine,
>BIOS Google 01/01/2011
>Workqueue: netns cleanup_net
>Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef
>lib/dump_stack.c:118
> print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
> kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354 kasan_report
>mm/kasan/report.c:412 [inline]
> __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
> tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165 tipc_topsrv_stop
>net/tipc/topsrv.c:701 [inline]
> tipc_topsrv_exit_net+0x27b/0x5c0 net/tipc/topsrv.c:722
> ops_exit_list+0xa5/0x150 net/core/net_namespace.c:153
> cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553
> process_one_work+0x864/0x1570 kernel/workqueue.c:2153
> worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
> kthread+0x33f/0x460 kernel/kthread.c:259
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
>
>Allocated by task 23:
> kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625 kmalloc
>include/linux/slab.h:515 [inline] kzalloc include/linux/slab.h:709 [inline]
> tipc_conn_alloc+0x43/0x4f0 net/tipc/topsrv.c:192
> tipc_topsrv_accept+0x1b5/0x280 net/tipc/topsrv.c:470
> process_one_work+0x864/0x1570 kernel/workqueue.c:2153
> worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
> kthread+0x33f/0x460 kernel/kthread.c:259
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
>
>Freed by task 23:
> __cache_free mm/slab.c:3503 [inline]
> kfree+0xcc/0x210 mm/slab.c:3822
> tipc_conn_kref_release net/tipc/topsrv.c:150 [inline] kref_put
>include/linux/kref.h:70 [inline]
> conn_put+0x2cd/0x3a0 net/tipc/topsrv.c:155
> process_one_work+0x864/0x1570 kernel/workqueue.c:2153
> worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
> kthread+0x33f/0x460 kernel/kthread.c:259
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
>
>The buggy address belongs to the object at ffff888099305a00 which belongs to
>the cache kmalloc-512 of size 512 The buggy address is located 8 bytes inside
>of 512-byte region [ffff888099305a00, ffff888099305c00) The buggy address
>belongs to the page:
>page:ffffea000264c140 count:1 mapcount:0 mapping:ffff88813bff0940
>index:0x0
>flags: 0xfff00000000100(slab)
>raw: 00fff00000000100 ffffea00028b6b88 ffffea0002cd2b08 ffff88813bff0940
>raw: 0000000000000000 ffff888099305000 0000000100000006
>0000000000000000 page dumped because: kasan: bad access detected
>
>Memory state around the buggy address:
> ffff888099305900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888099305980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>ffff888099305a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff888099305a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888099305b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>Fixes: c5fa7b3cf3cb ("tipc: introduce new TIPC server infrastructure")
>Reported-by: syzbot+d333febcf8f4bc5f6110@syzkaller.appspotmail.com
>Closes: https://syzkaller.appspot.com/bug?extid=27169a847a70550d17be
>Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
>---
> net/tipc/topsrv.c | 2 ++
> 1 file changed, 2 insertions(+)
>
>diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c index
>8ee0c07d00e9..ffe577bf6b51 100644
>--- a/net/tipc/topsrv.c
>+++ b/net/tipc/topsrv.c
>@@ -704,8 +704,10 @@ static void tipc_topsrv_stop(struct net *net)
> for (id = 0; srv->idr_in_use; id++) {
> con = idr_find(&srv->conn_idr, id);
> if (con) {
>+ conn_get(con);
> spin_unlock_bh(&srv->idr_lock);
> tipc_conn_close(con);
>+ conn_put(con);
> spin_lock_bh(&srv->idr_lock);
> }
> }
>--
>2.50.0.727.gbf7dc18ff4-goog
>
Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close().
2025-07-02 1:43 [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close() Kuniyuki Iwashima
2025-07-02 6:34 ` Tung Quang Nguyen
@ 2025-07-08 2:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-07-08 2:00 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: jmaloy, davem, edumazet, kuba, pabeni, horms, ying.xue, kuni1840,
netdev, tipc-discussion, syzbot+d333febcf8f4bc5f6110
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Wed, 2 Jul 2025 01:43:40 +0000 you wrote:
> syzbot reported a null-ptr-deref in tipc_conn_close() during netns
> dismantle. [0]
>
> tipc_topsrv_stop() iterates tipc_net(net)->topsrv->conn_idr and calls
> tipc_conn_close() for each tipc_conn.
>
> The problem is that tipc_conn_close() is called after releasing the
> IDR lock.
>
> [...]
Here is the summary with links:
- [v1,net] tipc: Fix use-after-free in tipc_conn_close().
https://git.kernel.org/netdev/net/c/667eeab4999e
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
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2025-07-02 1:43 [PATCH v1 net] tipc: Fix use-after-free in tipc_conn_close() Kuniyuki Iwashima
2025-07-02 6:34 ` Tung Quang Nguyen
2025-07-08 2:00 ` patchwork-bot+netdevbpf
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