Re: [PATCH] ata: libahci_platform: ahci_platform_find_clk: oops, NULL pointer

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 12/6/22 17:34, Anders Roxell wrote:
> When booting a arm 32-bit kernel with config CONFIG_AHCI_DWC enabled on
> a am57xx-evm board. This happens when the clock references are unnamed
> in DT, the strcmp() produces a NULL pointer dereference, see the
> following oops, NULL pointer dereference:
> 
> [    4.673950] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> [    4.682098] [00000000] *pgd=00000000
> [    4.685699] Internal error: Oops: 5 [#1] SMP ARM
> [    4.690338] Modules linked in:
> [    4.693420] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0-rc7 #1
> [    4.699615] Hardware name: Generic DRA74X (Flattened Device Tree)
> [    4.705749] PC is at strcmp+0x0/0x34
> [    4.709350] LR is at ahci_platform_find_clk+0x3c/0x5c
> [    4.714416] pc : [<c130c494>]    lr : [<c0c230e0>]    psr: 20000013
> [    4.720703] sp : f000dda8  ip : 00000001  fp : c29b1840
> [    4.725952] r10: 00000020  r9 : c1b23380  r8 : c1b23368
> [    4.731201] r7 : c1ab4cc4  r6 : 00000001  r5 : c3c66040  r4 : 00000000
> [    4.737762] r3 : 00000080  r2 : 00000080  r1 : c1ab4cc4  r0 : 00000000
> [...]
> [    4.998870]  strcmp from ahci_platform_find_clk+0x3c/0x5c
> [    5.004302]  ahci_platform_find_clk from ahci_dwc_probe+0x1f0/0x54c
> [    5.010589]  ahci_dwc_probe from platform_probe+0x64/0xc0
> [    5.016021]  platform_probe from really_probe+0xe8/0x41c
> [    5.021362]  really_probe from __driver_probe_device+0xa4/0x204
> [    5.027313]  __driver_probe_device from driver_probe_device+0x38/0xc8
> [    5.033782]  driver_probe_device from __driver_attach+0xb4/0x1ec
> [    5.039825]  __driver_attach from bus_for_each_dev+0x78/0xb8
> [    5.045532]  bus_for_each_dev from bus_add_driver+0x17c/0x220
> [    5.051300]  bus_add_driver from driver_register+0x90/0x124
> [    5.056915]  driver_register from do_one_initcall+0x48/0x1e8
> [    5.062591]  do_one_initcall from kernel_init_freeable+0x1cc/0x234
> [    5.068817]  kernel_init_freeable from kernel_init+0x20/0x13c
> [    5.074584]  kernel_init from ret_from_fork+0x14/0x2c
> [    5.079681] Exception stack(0xf000dfb0 to 0xf000dff8)
> [    5.084747] dfa0:                                     00000000 00000000 00000000 00000000
> [    5.092956] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [    5.101165] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [    5.107818] Code: e5e32001 e3520000 1afffffb e12fff1e (e4d03001)
> [    5.114013] ---[ end trace 0000000000000000 ]---
> 
> Add an extra check in the if-statement if hpriv-clks[i].id.
> 
> Fixes: 6ce73f3a6fc0 ("ata: libahci_platform: Add function returning a clock-handle by id")
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

Applied to for-6.1-fixes. Thanks !

-- 
Damien Le Moal
Western Digital Research