netdev - Re: [PATCH net-next] bpf: fix a possible NULL deref in bpf_map_offload_map

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Message-ID: <Z8sPEqJ55AX7qKWN@mini-arch>
Date: Fri, 7 Mar 2025 07:21:54 -0800
From: Stanislav Fomichev <stfomichev@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Simon Horman <horms@...nel.org>, netdev@...r.kernel.org,
	eric.dumazet@...il.com,
	syzbot+0c7bfd8cf3aecec92708@...kaller.appspotmail.com
Subject: Re: [PATCH net-next] bpf: fix a possible NULL deref in
 bpf_map_offload_map_alloc()

On 03/07, Eric Dumazet wrote:
> Call bpf_dev_offload_check() before netdev_lock_ops().
> 
> This is needed if attr->map_ifindex is not valid.
> 
> Oops: general protection fault, probably for non-canonical address 0xdffffc0000000197: 0000 [#1] PREEMPT SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000cb8-0x0000000000000cbf]
>  RIP: 0010:netdev_need_ops_lock include/linux/netdevice.h:2792 [inline]
>  RIP: 0010:netdev_lock_ops include/linux/netdevice.h:2803 [inline]
>  RIP: 0010:bpf_map_offload_map_alloc+0x19a/0x910 kernel/bpf/offload.c:533
> Call Trace:
>  <TASK>
>   map_create+0x946/0x11c0 kernel/bpf/syscall.c:1455
>   __sys_bpf+0x6d3/0x820 kernel/bpf/syscall.c:5777
>   __do_sys_bpf kernel/bpf/syscall.c:5902 [inline]
>   __se_sys_bpf kernel/bpf/syscall.c:5900 [inline]
>   __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5900
>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> 
> Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf")
> Reported-by: syzbot+0c7bfd8cf3aecec92708@...kaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/67caa2b1.050a0220.15b4b9.0077.GAE@google.com/T/#u
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Oops, thanks for a quick fix!

Acked-by: Stanislav Fomichev <sdf@...ichev.me>