netdev - Re: [PATCH net] pptp: fix pptp

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Message-Id: 
 <175457820772.3587247.13197311955004551563.git-patchwork-notify@kernel.org>
Date: Thu, 07 Aug 2025 14:50:07 +0000
From: patchwork-bot+netdevbpf@...nel.org
To: Eric Dumazet <edumazet@...gle.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
 netdev@...r.kernel.org, eric.dumazet@...il.com,
 syzbot+27d7cfbc93457e472e00@...kaller.appspotmail.com
Subject: Re: [PATCH net] pptp: fix pptp_xmit() error path

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@...nel.org>:

On Thu,  7 Aug 2025 14:21:46 +0000 you wrote:
> I accidentally added a bug in pptp_xmit() that syzbot caught for us.
> 
> Only call ip_rt_put() if a route has been allocated.
> 
> BUG: unable to handle page fault for address: ffffffffffffffdb
> PGD df3b067 P4D df3b067 PUD df3d067 PMD 0
> Oops: Oops: 0002 [#1] SMP KASAN PTI
> CPU: 1 UID: 0 PID: 6346 Comm: syz.0.336 Not tainted 6.16.0-next-20250804-syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> RIP: 0010:arch_atomic_add_return arch/x86/include/asm/atomic.h:85 [inline]
> RIP: 0010:raw_atomic_sub_return_release include/linux/atomic/atomic-arch-fallback.h:846 [inline]
> RIP: 0010:atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:327 [inline]
> RIP: 0010:__rcuref_put include/linux/rcuref.h:109 [inline]
> RIP: 0010:rcuref_put+0x172/0x210 include/linux/rcuref.h:173
> Call Trace:
>  <TASK>
>  dst_release+0x24/0x1b0 net/core/dst.c:167
>  ip_rt_put include/net/route.h:285 [inline]
>  pptp_xmit+0x14b/0x1a90 drivers/net/ppp/pptp.c:267
>  __ppp_channel_push+0xf2/0x1c0 drivers/net/ppp/ppp_generic.c:2166
>  ppp_channel_push+0x123/0x660 drivers/net/ppp/ppp_generic.c:2198
>  ppp_write+0x2b0/0x400 drivers/net/ppp/ppp_generic.c:544
>  vfs_write+0x27b/0xb30 fs/read_write.c:684
>  ksys_write+0x145/0x250 fs/read_write.c:738
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> [...]

Here is the summary with links:
  - [net] pptp: fix pptp_xmit() error path
    https://git.kernel.org/netdev/net/c/ae633388cae3

You are awesome, thank you!
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