Re: [PATCH v2] spi: fsl-dspi: fix NULL pointer dereference

[Krzysztof Kozlowski]

On Mon, Sep 28, 2020 at 10:32:38AM +0200, Michael Walle wrote:
> Since commit 530b5affc675 ("spi: fsl-dspi: fix use-after-free in remove
> path") this driver causes a kernel oops:
> 
> [    1.891065] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000080
> [    1.899889] Mem abort info:
> [    1.902692]   ESR = 0x96000004
> [    1.905754]   EC = 0x25: DABT (current EL), IL = 32 bits
> [    1.911089]   SET = 0, FnV = 0
> [    1.914156]   EA = 0, S1PTW = 0
> [    1.917303] Data abort info:
> [    1.920193]   ISV = 0, ISS = 0x00000004
> [    1.924044]   CM = 0, WnR = 0
> [    1.927022] [0000000000000080] user address but active_mm is swapper
> [    1.933403] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [    1.938995] Modules linked in:
> [    1.942060] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc6-next-20200925-00026-gae556cc74e28-dirty #94
> [    1.951838] Hardware name: Kontron SMARC-sAL28 (Single PHY) on SMARC Eval 2.0 carrier (DT)
> [    1.960135] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--)
> [    1.966168] pc : dspi_setup+0xc8/0x2e0
> [    1.969926] lr : dspi_setup+0xbc/0x2e0
> [    1.973684] sp : ffff80001139b930
> [    1.977005] x29: ffff80001139b930 x28: ffff00207a5d2000
> [    1.982338] x27: 0000000000000006 x26: ffff00207a44d410
> [    1.987669] x25: ffff002079c08100 x24: ffff00207a5d2400
> [    1.993000] x23: ffff00207a5d2600 x22: ffff800011169948
> [    1.998332] x21: ffff800010cbcd20 x20: ffff00207a58a800
> [    2.003663] x19: ffff00207a76b700 x18: 0000000000000010
> [    2.008994] x17: 0000000000000001 x16: 0000000000000019
> [    2.014326] x15: ffffffffffffffff x14: 0720072007200720
> [    2.019657] x13: 0720072007200720 x12: ffff8000111fc5e0
> [    2.024989] x11: 0000000000000003 x10: ffff8000111e45a0
> [    2.030320] x9 : 0000000000000000 x8 : ffff00207a76b780
> [    2.035651] x7 : 0000000000000000 x6 : 000000000000003f
> [    2.040982] x5 : 0000000000000040 x4 : ffff80001139b918
> [    2.046313] x3 : 0000000000000001 x2 : 64b62cc917af5100
> [    2.051643] x1 : 0000000000000000 x0 : 0000000000000000

You can skip all these addresses/registers, so only keep OOPS message
and call trace.

Reviewed-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>

Best regards,
Krzysztof