Re: [PATCH 3/3] x86/MCE/AMD: Get address from already initialized block

[Johannes Hirte]

On 2018 Feb 01, Yazen Ghannam wrote:
> From: Yazen Ghannam <yazen.ghannam@xxxxxxx>
> 
> The block address is saved after the block is initialized when
> threshold_init_device() is called.
> 
> Use the saved block address, if available, rather than trying to
> rediscover it.
> 
> We can avoid some *on_cpu() calls in the init path that will cause a
> call trace when resuming from suspend.
> 
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.14.x
> Signed-off-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>
> ---
>  arch/x86/kernel/cpu/mcheck/mce_amd.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> index bf53b4549a17..8c4f8f30c779 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> @@ -436,6 +436,21 @@ static u32 get_block_address(unsigned int cpu, u32 current_addr, u32 low, u32 hi
>  {
>  	u32 addr = 0, offset = 0;
>  
> +	if ((bank >= mca_cfg.banks) || (block >= NR_BLOCKS))
> +		return addr;
> +
> +	/* Get address from already initialized block. */
> +	if (per_cpu(threshold_banks, cpu)) {
> +		struct threshold_bank *bankp = per_cpu(threshold_banks, cpu)[bank];
> +
> +		if (bankp && bankp->blocks) {
> +			struct threshold_block *blockp = &bankp->blocks[block];
> +
> +			if (blockp)
> +				return blockp->address;
> +		}
> +	}
> +
>  	if (mce_flags.smca) {
>  		if (smca_get_bank_type(bank) == SMCA_RESERVED)
>  			return addr;
> -- 
> 2.14.1

I have a KASAN: slab-out-of-bounds, and git bisect points me to this
change:

Apr 13 00:40:32 probook kernel: ==================================================================
Apr 13 00:40:32 probook kernel: BUG: KASAN: slab-out-of-bounds in get_block_address.isra.3+0x1e9/0x520
Apr 13 00:40:32 probook kernel: Read of size 4 at addr ffff8803f165ddf4 by task swapper/0/1
Apr 13 00:40:32 probook kernel: 
Apr 13 00:40:32 probook kernel: CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.16.0-10757-g4ca8ba4ccff9 #532
Apr 13 00:40:32 probook kernel: Hardware name: HP HP ProBook 645 G2/80FE, BIOS N77 Ver. 01.12 12/19/2017
Apr 13 00:40:32 probook kernel: Call Trace:
Apr 13 00:40:32 probook kernel:  dump_stack+0x5b/0x8b
Apr 13 00:40:32 probook kernel:  ? get_block_address.isra.3+0x1e9/0x520
Apr 13 00:40:32 probook kernel:  print_address_description+0x65/0x270
Apr 13 00:40:32 probook kernel:  ? get_block_address.isra.3+0x1e9/0x520
Apr 13 00:40:32 probook kernel:  kasan_report+0x232/0x350
Apr 13 00:40:32 probook kernel:  get_block_address.isra.3+0x1e9/0x520
Apr 13 00:40:32 probook kernel:  ? kobject_init_and_add+0xde/0x130
Apr 13 00:40:32 probook kernel:  ? get_name+0x390/0x390
Apr 13 00:40:32 probook kernel:  ? kasan_unpoison_shadow+0x30/0x40
Apr 13 00:40:32 probook kernel:  ? kasan_kmalloc+0xa0/0xd0
Apr 13 00:40:32 probook kernel:  allocate_threshold_blocks+0x12c/0xc60
Apr 13 00:40:32 probook kernel:  ? kobject_add_internal+0x800/0x800
Apr 13 00:40:32 probook kernel:  ? get_block_address.isra.3+0x520/0x520
Apr 13 00:40:32 probook kernel:  ? kasan_kmalloc+0xa0/0xd0
Apr 13 00:40:32 probook kernel:  mce_threshold_create_device+0x35b/0x990
Apr 13 00:40:32 probook kernel:  ? init_special_inode+0x1d0/0x230
Apr 13 00:40:32 probook kernel:  threshold_init_device+0x98/0xa7
Apr 13 00:40:32 probook kernel:  ? mcheck_vendor_init_severity+0x43/0x43
Apr 13 00:40:32 probook kernel:  do_one_initcall+0x76/0x30c
Apr 13 00:40:32 probook kernel:  ? trace_event_raw_event_initcall_finish+0x190/0x190
Apr 13 00:40:32 probook kernel:  ? kasan_unpoison_shadow+0xb/0x40
Apr 13 00:40:32 probook kernel:  ? kasan_unpoison_shadow+0x30/0x40
Apr 13 00:40:32 probook kernel:  kernel_init_freeable+0x3d6/0x471
Apr 13 00:40:32 probook kernel:  ? rest_init+0xf0/0xf0
Apr 13 00:40:32 probook kernel:  kernel_init+0xa/0x120
Apr 13 00:40:32 probook kernel:  ? rest_init+0xf0/0xf0
Apr 13 00:40:32 probook kernel:  ret_from_fork+0x22/0x40
Apr 13 00:40:32 probook kernel:
Apr 13 00:40:32 probook kernel: Allocated by task 1:
Apr 13 00:40:32 probook kernel:  kasan_kmalloc+0xa0/0xd0
Apr 13 00:40:32 probook kernel:  kmem_cache_alloc_trace+0xf3/0x1f0
Apr 13 00:40:32 probook kernel:  allocate_threshold_blocks+0x1bc/0xc60
Apr 13 00:40:32 probook kernel:  mce_threshold_create_device+0x35b/0x990
Apr 13 00:40:32 probook kernel:  threshold_init_device+0x98/0xa7
Apr 13 00:40:32 probook kernel:  do_one_initcall+0x76/0x30c
Apr 13 00:40:32 probook kernel:  kernel_init_freeable+0x3d6/0x471
Apr 13 00:40:32 probook kernel:  kernel_init+0xa/0x120
Apr 13 00:40:32 probook kernel:  ret_from_fork+0x22/0x40
Apr 13 00:40:32 probook kernel: 
Apr 13 00:40:32 probook kernel: Freed by task 0:
Apr 13 00:40:32 probook kernel: (stack is not available)
Apr 13 00:40:32 probook kernel: 
Apr 13 00:40:32 probook kernel: The buggy address belongs to the object at ffff8803f165dd80
 which belongs to the cache kmalloc-128 of size 128
Apr 13 00:40:32 probook kernel: The buggy address is located 116 bytes inside of
 128-byte region [ffff8803f165dd80, ffff8803f165de00)
 Apr 13 00:40:32 probook kernel: The buggy address belongs to the page:
Apr 13 00:40:32 probook kernel: page:ffffea000fc59740 count:1 mapcount:0 mapping:0000000000000000 index:0x0
Apr 13 00:40:32 probook kernel: flags: 0x2000000000000100(slab)
Apr 13 00:40:32 probook kernel: raw: 2000000000000100 0000000000000000 0000000000000000 0000000180150015
Apr 13 00:40:32 probook kernel: raw: dead000000000100 dead000000000200 ffff8803f3403340 0000000000000000
Apr 13 00:40:32 probook kernel: page dumped because: kasan: bad access detected
Apr 13 00:40:32 probook kernel: 
Apr 13 00:40:32 probook kernel: Memory state around the buggy address:
Apr 13 00:40:32 probook kernel:  ffff8803f165dc80: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
Apr 13 00:40:32 probook kernel:  ffff8803f165dd00: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
Apr 13 00:40:32 probook kernel: >ffff8803f165dd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
Apr 13 00:40:32 probook kernel:                                                              ^
Apr 13 00:40:32 probook kernel:  ffff8803f165de00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
Apr 13 00:40:32 probook kernel:  ffff8803f165de80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
Apr 13 00:40:32 probook kernel: ==================================================================

-- 
Regards,
  Johannes