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Message-ID: <101d3fc0-0cb4-444b-9c67-9142610ad1dc@windriver.com>
Date: Wed, 14 May 2025 09:34:52 +0800
From: Yun Zhou <yun.zhou@...driver.com>
To: mturquette@...libre.com, sboyd@...nel.org, dianders@...omium.org
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: fix slab-use-after-free when
clk_core_populate_parent_map failed
Hi Michael,
Could you please take a moment to help me review the patch?
Thanks,
Yun
On 4/25/25 13:23, Yun Zhou wrote:
> If clk_core_populate_parent_map() fails, core->parents will be immediately
> released within clk_core_populate_parent_map(). Therefore it is can't be
> released in __clk_release() again.
>
> This fixes the following KASAN reported issue:
>
> ==================================================================
> BUG: KASAN: slab-use-after-free in __clk_release+0x80/0x160
> Read of size 8 at addr ffffff8043fd0980 by task kworker/u6:0/27
>
> CPU: 1 PID: 27 Comm: kworker/u6:0 Tainted: G W 6.6.69-yocto-standard+ #7
> Hardware name: Raspberry Pi 4 Model B (DT)
> Workqueue: events_unbound deferred_probe_work_func
> Call trace:
> dump_backtrace+0x98/0xf8
> show_stack+0x20/0x38
> dump_stack_lvl+0x48/0x60
> print_report+0xf8/0x5d8
> kasan_report+0xb4/0x100
> __asan_load8+0x9c/0xc0
> __clk_release+0x80/0x160
> __clk_register+0x6dc/0xfb8
> devm_clk_hw_register+0x70/0x108
> bcm2835_register_clock+0x284/0x358
> bcm2835_clk_probe+0x2c4/0x438
> platform_probe+0x98/0x110
> really_probe+0x1e4/0x3e8
> __driver_probe_device+0xc0/0x1a0
> driver_probe_device+0x110/0x1e8
> __device_attach_driver+0xf0/0x1a8
> bus_for_each_drv+0xf8/0x178
> __device_attach+0x120/0x240
> device_initial_probe+0x1c/0x30
> bus_probe_device+0xdc/0xe8
> deferred_probe_work_func+0xe8/0x130
> process_one_work+0x2a4/0x698
> worker_thread+0x53c/0x708
> kthread+0x1b4/0x1c8
> ret_from_fork+0x10/0x20
>
> Allocated by task 27:
> kasan_save_stack+0x3c/0x68
> kasan_set_track+0x2c/0x40
> kasan_save_alloc_info+0x24/0x38
> __kasan_kmalloc+0xd4/0xd8
> __kmalloc+0x74/0x238
> __clk_register+0x718/0xfb8
> devm_clk_hw_register+0x70/0x108
> bcm2835_register_clock+0x284/0x358
> bcm2835_clk_probe+0x2c4/0x438
> platform_probe+0x98/0x110
> really_probe+0x1e4/0x3e8
> __driver_probe_device+0xc0/0x1a0
> driver_probe_device+0x110/0x1e8
> __device_attach_driver+0xf0/0x1a8
> bus_for_each_drv+0xf8/0x178
> __device_attach+0x120/0x240
> device_initial_probe+0x1c/0x30
> bus_probe_device+0xdc/0xe8
> deferred_probe_work_func+0xe8/0x130
> process_one_work+0x2a4/0x698
> worker_thread+0x53c/0x708
> kthread+0x1b4/0x1c8
> ret_from_fork+0x10/0x20
>
> Freed by task 27:
> kasan_save_stack+0x3c/0x68
> kasan_set_track+0x2c/0x40
> kasan_save_free_info+0x38/0x60
> __kasan_slab_free+0x100/0x170
> slab_free_freelist_hook+0xcc/0x218
> __kmem_cache_free+0x158/0x210
> kfree+0x88/0x140
> __clk_register+0x9d0/0xfb8
> devm_clk_hw_register+0x70/0x108
> bcm2835_register_clock+0x284/0x358
> bcm2835_clk_probe+0x2c4/0x438
> platform_probe+0x98/0x110
> really_probe+0x1e4/0x3e8
> __driver_probe_device+0xc0/0x1a0
> driver_probe_device+0x110/0x1e8
> __device_attach_driver+0xf0/0x1a8
> bus_for_each_drv+0xf8/0x178
> __device_attach+0x120/0x240
> device_initial_probe+0x1c/0x30
> bus_probe_device+0xdc/0xe8
> deferred_probe_work_func+0xe8/0x130
> process_one_work+0x2a4/0x698
> worker_thread+0x53c/0x708
> kthread+0x1b4/0x1c8
> ret_from_fork+0x10/0x20
>
> The buggy address belongs to the object at ffffff8043fd0800
> which belongs to the cache kmalloc-512 of size 512
> The buggy address is located 384 bytes inside of
> freed 512-byte region [ffffff8043fd0800, ffffff8043fd0a00)
>
> The buggy address belongs to the physical page:
> page:fffffffe010ff400 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffffff8043fd0e00 pfn:0x43fd0
> head:fffffffe010ff400 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0x4000000000000840(slab|head|zone=1)
> page_type: 0xffffffff()
> raw: 4000000000000840 ffffff8040002f40 ffffff8040000a50 ffffff8040000a50
> raw: ffffff8043fd0e00 0000000000150002 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffffff8043fd0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffffff8043fd0900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffffff8043fd0980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffffff8043fd0a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffffff8043fd0a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
>
> Fixes: 9d05ae531c2c ("clk: Initialize struct clk_core kref earlier")
> Signed-off-by: Yun Zhou <yun.zhou@...driver.com>
> ---
> drivers/clk/clk.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 0565c87656cf..3f89ed51d4a4 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -4242,7 +4242,6 @@ static int clk_core_populate_parent_map(struct clk_core *core,
> * having a cache of names/clk_hw pointers to clk_core pointers.
> */
> parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
> - core->parents = parents;
> if (!parents)
> return -ENOMEM;
>
> @@ -4283,6 +4282,8 @@ static int clk_core_populate_parent_map(struct clk_core *core,
> }
> }
>
> + core->parents = parents;
> +
> return 0;
> }
>
> @@ -4290,7 +4291,7 @@ static void clk_core_free_parent_map(struct clk_core *core)
> {
> int i = core->num_parents;
>
> - if (!core->num_parents)
> + if (!core->parents)
> return;
>
> while (--i >= 0) {
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