Re: HW-KASAN and CONFIG_SLUB_DEBUG_ON=y screams about redzone corruption

[Alexander Potapenko <glider@google.com>]

On Wed, Jun 28, 2023 at 5:47 PM Will Deacon <will@kernel.org> wrote:
>
> Hi memory tagging folks,
>
> While debugging something else, I ended up running v6.4 on an arm64 (v9)
> fastmodel with both CONFIG_SLUB_DEBUG_ON=y and CONFIG_KASAN_HW_TAGS=y.
> This makes the system pretty unusable, as I see a tonne of kmalloc
> Redzone corruption messages pretty much straight out of startup (example
> below).
>
> Please can you take a look?
>
> Cheers,
Does the problem reproduce with CONFIG_KASAN_SW_TAGS?
Also, any chance you could share the file:line info for the stack trace below?

I myself haven't expected KASAN to work together with SLUB_DEBUG...

>
> Will
>
> --->8
>
> [    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1
> [    0.000000] =============================================================================
> [    0.000000] BUG kmalloc-128 (Not tainted): kmalloc Redzone overwritten
> [    0.000000] -----------------------------------------------------------------------------
> [    0.000000]
> [    0.000000] 0xffff00080001a9b0-0xf1ff00080001a9ff @offset=2480. First byte 0x0 instead of 0xcc
> [    0.000000] Allocated in apply_wqattrs_prepare+0x90/0x2a4 age=0 cpu=0 pid=0
> [    0.000000]  kmalloc_trace+0x34/0x6c
> [    0.000000]  apply_wqattrs_prepare+0x90/0x2a4
> [    0.000000]  apply_workqueue_attrs+0x5c/0xb4
> [    0.000000]  alloc_workqueue+0x368/0x4f8
> [    0.000000]  workqueue_init_early+0x2e8/0x3ac
> [    0.000000]  start_kernel+0x168/0x394
> [    0.000000]  __primary_switched+0xbc/0xc4
> [    0.000000] Slab 0xfffffc0020000680 objects=21 used=8 fp=0xffff00080001ac80 flags=0xbfffc0000010200(slab|head|node=0|zone=2|lastcpupid=0xffff|kasantag=0x0)
> [    0.000000] Object 0xf1ff00080001a980 @offset=17437937757178562944 fp=0x0000000000000000
> [    0.000000]
> [    0.000000] Redzone  ffff00080001a900: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a910: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a920: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a930: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a940: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a950: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a960: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Redzone  ffff00080001a970: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................
> [    0.000000] Object   ffff00080001a980: 00 00 00 00 00 00 00 00 ff 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a990: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a9a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a9b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a9c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a9d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a9e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Object   ffff00080001a9f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> [    0.000000] Redzone  ffff00080001aa00: cc cc cc cc cc cc cc cc                          ........
> [    0.000000] Padding  ffff00080001aa54: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a  ZZZZZZZZZZZZZZZZ
> [    0.000000] Padding  ffff00080001aa64: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a  ZZZZZZZZZZZZZZZZ
> [    0.000000] Padding  ffff00080001aa74: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a              ZZZZZZZZZZZZ
> [    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.4.0-00001-g56e11237836c #1
> [    0.000000] Hardware name: FVP Base RevC (DT)
> [    0.000000] Call trace:
> [    0.000000]  dump_backtrace+0xec/0x108
> [    0.000000]  show_stack+0x18/0x2c
> [    0.000000]  dump_stack_lvl+0x50/0x68
> [    0.000000]  dump_stack+0x18/0x24
> [    0.000000]  print_trailer+0x1ec/0x230
> [    0.000000]  check_bytes_and_report+0x110/0x154
> [    0.000000]  check_object+0x31c/0x360
> [    0.000000]  free_to_partial_list+0x174/0x5d8
> [    0.000000]  __slab_free+0x220/0x28c
> [    0.000000]  __kmem_cache_free+0x364/0x3dc
> [    0.000000]  kfree+0x50/0x70
> [    0.000000]  apply_wqattrs_prepare+0x244/0x2a4
> [    0.000000]  apply_workqueue_attrs+0x5c/0xb4
> [    0.000000]  alloc_workqueue+0x368/0x4f8
> [    0.000000]  workqueue_init_early+0x2e8/0x3ac
> [    0.000000]  start_kernel+0x168/0x394
> [    0.000000]  __primary_switched+0xbc/0xc4
> [    0.000000] Disabling lock debugging due to kernel taint
> [    0.000000] FIX kmalloc-128: Restoring kmalloc Redzone 0xffff00080001a9b0-0xf1ff00080001a9ff=0xcc
> [    0.000000] FIX kmalloc-128: Object at 0xf1ff00080001a980 not freed
>
>
>
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-- 
Alexander Potapenko
Software Engineer

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