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Message-ID: <20250422122832.GE2843373@horms.kernel.org>
Date: Tue, 22 Apr 2025 13:28:32 +0100
From: Simon Horman <horms@...nel.org>
To: Tung Nguyen <tung.quang.nguyen@....tech>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
edumazet@...gle.com, pabeni@...hat.com, jmaloy@...hat.com,
syzbot+ed60da8d686dc709164c@...kaller.appspotmail.com,
Hoang Le <hoang.h.le@...tech.com.au>,
tipc-discussion@...ts.sourceforge.net
Subject: Re: [PATCH net] tipc: fix NULL pointer dereference in
tipc_mon_reinit_self()
+ Hoang Le, tipc-discussion
On Thu, Apr 17, 2025 at 02:47:15PM +0700, Tung Nguyen wrote:
> syzbot reported:
>
> tipc: Node number set to 1055423674
> Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
> CPU: 3 UID: 0 PID: 6017 Comm: kworker/3:5 Not tainted 6.15.0-rc1-syzkaller-00246-g900241a5cc15 #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> Workqueue: events tipc_net_finalize_work
> RIP: 0010:tipc_mon_reinit_self+0x11c/0x210 net/tipc/monitor.c:719
> ...
> RSP: 0018:ffffc9000356fb68 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000003ee87cba
> RDX: 0000000000000000 RSI: ffffffff8dbc56a7 RDI: ffff88804c2cc010
> RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000007
> R13: fffffbfff2111097 R14: ffff88804ead8000 R15: ffff88804ead9010
> FS: 0000000000000000(0000) GS:ffff888097ab9000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000f720eb00 CR3: 000000000e182000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> tipc_net_finalize+0x10b/0x180 net/tipc/net.c:140
> process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
> process_scheduled_works kernel/workqueue.c:3319 [inline]
> worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
> kthread+0x3c2/0x780 kernel/kthread.c:464
> ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> </TASK>
> ...
> RIP: 0010:tipc_mon_reinit_self+0x11c/0x210 net/tipc/monitor.c:719
> ...
> RSP: 0018:ffffc9000356fb68 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000003ee87cba
> RDX: 0000000000000000 RSI: ffffffff8dbc56a7 RDI: ffff88804c2cc010
> RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000007
> R13: fffffbfff2111097 R14: ffff88804ead8000 R15: ffff88804ead9010
> FS: 0000000000000000(0000) GS:ffff888097ab9000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000f720eb00 CR3: 000000000e182000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
> There is a racing condition between workqueue created when enabling
> bearer and another thread created when disabling bearer right after
> that as follow:
>
> enabling_bearer | disabling_bearer
> --------------- | ----------------
> tipc_disc_timeout() |
> { | bearer_disable()
> ... | {
> schedule_work(&tn->work); | tipc_mon_delete()
> ... | {
> } | ...
> | write_lock_bh(&mon->lock);
> | mon->self = NULL;
> | write_unlock_bh(&mon->lock);
> | ...
> | }
> tipc_net_finalize_work() | }
> { |
> ... |
> tipc_net_finalize() |
> { |
> ... |
> tipc_mon_reinit_self() |
> { |
> ... |
> write_lock_bh(&mon->lock); |
> mon->self->addr = tipc_own_addr(net); |
> write_unlock_bh(&mon->lock); |
> ... |
> } |
> ... |
> } |
> ... |
> } |
>
> 'mon->self' is set to NULL in disabling_bearer thread and dereferenced
> later in enabling_bearer thread.
>
> This commit fixes this issue by validating 'mon->self' before assigning
> node address to it.
>
> Reported-by: syzbot+ed60da8d686dc709164c@...kaller.appspotmail.com
> Fixes: 46cb01eeeb86 ("tipc: update mon's self addr when node addr generated")
> Signed-off-by: Tung Nguyen <tung.quang.nguyen@....tech>
Reviewed-by: Simon Horman <horms@...nel.org>
> ---
> net/tipc/monitor.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
> index e2f19627e43d..b45c5b91bc7a 100644
> --- a/net/tipc/monitor.c
> +++ b/net/tipc/monitor.c
> @@ -716,7 +716,8 @@ void tipc_mon_reinit_self(struct net *net)
> if (!mon)
> continue;
> write_lock_bh(&mon->lock);
> - mon->self->addr = tipc_own_addr(net);
> + if (mon->self)
> + mon->self->addr = tipc_own_addr(net);
> write_unlock_bh(&mon->lock);
> }
> }
> --
> 2.43.0
>
>
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