Re: [PATCH net] net: vertexcom: mse102x: Fix possible double free of TX skb

[Simon Horman]

On Tue, Oct 22, 2024 at 05:52:42PM +0200, Stefan Wahren wrote:
> The scope of the TX skb is wider than just mse102x_tx_frame_spi(),
> so in case the TX skb room needs to be expanded, also its pointer
> needs to be adjusted. Otherwise the already freed skb pointer would
> be freed again in mse102x_tx_work(), which leads to crashes:
> 
>   Internal error: Oops: 0000000096000004 [#2] PREEMPT SMP
>   CPU: 0 PID: 712 Comm: kworker/0:1 Tainted: G      D            6.6.23
>   Hardware name: chargebyte Charge SOM DC-ONE (DT)
>   Workqueue: events mse102x_tx_work [mse102x]
>   pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>   pc : skb_release_data+0xb8/0x1d8
>   lr : skb_release_data+0x1ac/0x1d8
>   sp : ffff8000819a3cc0
>   x29: ffff8000819a3cc0 x28: ffff0000046daa60 x27: ffff0000057f2dc0
>   x26: ffff000005386c00 x25: 0000000000000002 x24: 00000000ffffffff
>   x23: 0000000000000000 x22: 0000000000000001 x21: ffff0000057f2e50
>   x20: 0000000000000006 x19: 0000000000000000 x18: ffff00003fdacfcc
>   x17: e69ad452d0c49def x16: 84a005feff870102 x15: 0000000000000000
>   x14: 000000000000024a x13: 0000000000000002 x12: 0000000000000000
>   x11: 0000000000000400 x10: 0000000000000930 x9 : ffff00003fd913e8
>   x8 : fffffc00001bc008
>   x7 : 0000000000000000 x6 : 0000000000000008
>   x5 : ffff00003fd91340 x4 : 0000000000000000 x3 : 0000000000000009
>   x2 : 00000000fffffffe x1 : 0000000000000000 x0 : 0000000000000000
>   Call trace:
>    skb_release_data+0xb8/0x1d8
>    kfree_skb_reason+0x48/0xb0
>    mse102x_tx_work+0x164/0x35c [mse102x]
>    process_one_work+0x138/0x260
>    worker_thread+0x32c/0x438
>    kthread+0x118/0x11c
>    ret_from_fork+0x10/0x20
>   Code: aa1303e0 97fffab6 72001c1f 54000141 (f9400660)
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 2f207cbf0dd4 ("net: vertexcom: Add MSE102x SPI support")
> Signed-off-by: Stefan Wahren <wahrenst@xxxxxxx>

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>