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Message-ID: <CAJZ5v0ieDG6oNVtZ52zP592dYvPQBYOKMxtujiSbs19KT0MJag@mail.gmail.com>
Date: Thu, 17 Oct 2019 23:40:47 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: John Garry <john.garry@...wei.com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linuxarm <linuxarm@...wei.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / CPPC: Set pcc_data[pcc_ss_id] to NULL in acpi_cppc_processor_exit()
On Tue, Oct 15, 2019 at 4:10 PM John Garry <john.garry@...wei.com> wrote:
>
> When enabling KASAN and DEBUG_TEST_DRIVER_REMOVE, I find this KASAN
> warning:
>
> [ 20.872057] BUG: KASAN: use-after-free in pcc_data_alloc+0x40/0xb8
> [ 20.878226] Read of size 4 at addr ffff00236cdeb684 by task swapper/0/1
> [ 20.884826]
> [ 20.886309] CPU: 19 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc1-00009-ge7f7df3db5bf-dirty #289
> [ 20.894994] Hardware name: Huawei D06 /D06, BIOS Hisilicon D06 UEFI RC0 - V1.16.01 03/15/2019
> [ 20.903505] Call trace:
> [ 20.905942] dump_backtrace+0x0/0x200
> [ 20.909593] show_stack+0x14/0x20
> [ 20.912899] dump_stack+0xd4/0x130
> [ 20.916291] print_address_description.isra.9+0x6c/0x3b8
> [ 20.921592] __kasan_report+0x12c/0x23c
> [ 20.925417] kasan_report+0xc/0x18
> [ 20.928808] __asan_load4+0x94/0xb8
> [ 20.932286] pcc_data_alloc+0x40/0xb8
> [ 20.935938] acpi_cppc_processor_probe+0x4e8/0xb08
> [ 20.940717] __acpi_processor_start+0x48/0xb0
> [ 20.945062] acpi_processor_start+0x40/0x60
> [ 20.949235] really_probe+0x118/0x548
> [ 20.952887] driver_probe_device+0x7c/0x148
> [ 20.957059] device_driver_attach+0x94/0xa0
> [ 20.961231] __driver_attach+0xa4/0x110
> [ 20.965055] bus_for_each_dev+0xe8/0x158
> [ 20.968966] driver_attach+0x30/0x40
> [ 20.972531] bus_add_driver+0x234/0x2f0
> [ 20.976356] driver_register+0xbc/0x1d0
> [ 20.980182] acpi_processor_driver_init+0x40/0xe4
> [ 20.984875] do_one_initcall+0xb4/0x254
> [ 20.988700] kernel_init_freeable+0x24c/0x2f8
> [ 20.993047] kernel_init+0x10/0x118
> [ 20.996524] ret_from_fork+0x10/0x18
> [ 21.000087]
> [ 21.001567] Allocated by task 1:
> [ 21.004785] save_stack+0x28/0xc8
> [ 21.008089] __kasan_kmalloc.isra.9+0xbc/0xd8
> [ 21.012435] kasan_kmalloc+0xc/0x18
> [ 21.015913] pcc_data_alloc+0x94/0xb8
> [ 21.019564] acpi_cppc_processor_probe+0x4e8/0xb08
> [ 21.024343] __acpi_processor_start+0x48/0xb0
> [ 21.028689] acpi_processor_start+0x40/0x60
> [ 21.032860] really_probe+0x118/0x548
> [ 21.036512] driver_probe_device+0x7c/0x148
> [ 21.040684] device_driver_attach+0x94/0xa0
> [ 21.044855] __driver_attach+0xa4/0x110
> [ 21.048680] bus_for_each_dev+0xe8/0x158
> [ 21.052591] driver_attach+0x30/0x40
> [ 21.056155] bus_add_driver+0x234/0x2f0
> [ 21.059980] driver_register+0xbc/0x1d0
> [ 21.063805] acpi_processor_driver_init+0x40/0xe4
> [ 21.068497] do_one_initcall+0xb4/0x254
> [ 21.072322] kernel_init_freeable+0x24c/0x2f8
> [ 21.076667] kernel_init+0x10/0x118
> [ 21.080144] ret_from_fork+0x10/0x18
> [ 21.083707]
> [ 21.085186] Freed by task 1:
> [ 21.088056] save_stack+0x28/0xc8
> [ 21.091360] __kasan_slab_free+0x118/0x180
> [ 21.095445] kasan_slab_free+0x10/0x18
> [ 21.099183] kfree+0x80/0x268
> [ 21.102139] acpi_cppc_processor_exit+0x1a8/0x1b8
> [ 21.106832] acpi_processor_stop+0x70/0x80
> [ 21.110917] really_probe+0x174/0x548
> [ 21.114568] driver_probe_device+0x7c/0x148
> [ 21.118740] device_driver_attach+0x94/0xa0
> [ 21.122912] __driver_attach+0xa4/0x110
> [ 21.126736] bus_for_each_dev+0xe8/0x158
> [ 21.130648] driver_attach+0x30/0x40
> [ 21.134212] bus_add_driver+0x234/0x2f0
> [ 21.0x10/0x18
> [ 21.161764]
> [ 21.163244] The buggy address belongs to the object at ffff00236cdeb600
> [ 21.163244] which belongs to the cache kmalloc-256 of size 256
> [ 21.175750] The buggy address is located 132 bytes inside of
> [ 21.175750] 256-byte region [ffff00236cdeb600, ffff00236cdeb700)
> [ 21.187473] The buggy address belongs to the page:
> [ 21.192254] page:fffffe008d937a00 refcount:1 mapcount:0 mapping:ffff002370c0fa00 index:0x0 compound_mapcount: 0
> [ 21.202331] flags: 0x1ffff00000010200(slab|head)
> [ 21.206940] raw: 1ffff00000010200 dead000000000100 dead000000000122 ffff002370c0fa00
> [ 21.214671] raw: 0000000000000000 00000000802a002a 00000001ffffffff 0000000000000000
> [ 21.222400] page dumped because: kasan: bad access detected
> [ 21.227959]
> [ 21.229438] Memory state around the buggy address:
> [ 21.234218] ffff00236cdeb580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 21.241427] ffff00236cdeb600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> [ 21.248637] >ffff00236cdeb680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> [ 21.255845] ^
> [ 21.259062] ffff00236cdeb700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 21.266272] ffff00236cdeb780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> [ 21.273480] ==================================================================
>
> It seems that global pcc_data[pcc_ss_id] can be freed in
> acpi_cppc_processor_exit(), but we may later reference this value, so
> NULLify it when freed.
>
> Also remove the useless setting of data "pcc_channel_acquired", which
> we're about to free.
>
> Signed-off-by: John Garry <john.garry@...wei.com>
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 3b2525908dd8..a1a858ad4d18 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -905,8 +905,8 @@ void acpi_cppc_processor_exit(struct acpi_processor *pr)
> pcc_data[pcc_ss_id]->refcount--;
> if (!pcc_data[pcc_ss_id]->refcount) {
> pcc_mbox_free_channel(pcc_data[pcc_ss_id]->pcc_channel);
> - pcc_data[pcc_ss_id]->pcc_channel_acquired = 0;
> kfree(pcc_data[pcc_ss_id]);
> + pcc_data[pcc_ss_id] = NULL;
> }
> }
> }
> --
Applied as a fix for 5.4, thanks!
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