Messages in this thread | | | Date | Thu, 30 Sep 2021 09:35:36 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2] scs: Release kasan vmalloc poison in scs_free process |
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On Thu, Sep 30, 2021 at 04:16:13PM +0800, yee.lee@mediatek.com wrote: > From: Yee Lee <yee.lee@mediatek.com> > > Since scs allocation is moved to vmalloc region, the > shadow stack is protected by kasan_posion_vmalloc. > However, the vfree_atomic operation needs to access > its context for scs_free process and causes kasan error > as the dump info below. > > This patch Adds kasan_unpoison_vmalloc() before vfree_atomic, > which aligns to the prior flow as using kmem_cache. > The vmalloc region will go back posioned in the following > vumap() operations. > > ================================================================== > BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4 > Write of size 8 at addr ffff8000100b9000 by task kthreadd/2 > > CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-g92477dd1faa6-dirty #1 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace+0x0/0x43c > show_stack+0x1c/0x2c > dump_stack_lvl+0x68/0x84 > print_address_description+0x80/0x394 > kasan_report+0x180/0x1dc > __asan_report_store8_noabort+0x48/0x58 > llist_add_batch+0x60/0xd4 > vfree_atomic+0x60/0xe0 > scs_free+0x1dc/0x1fc > scs_release+0xa4/0xd4 > free_task+0x30/0xe4 > __put_task_struct+0x1ec/0x2e0 > delayed_put_task_struct+0x5c/0xa0 > rcu_do_batch+0x62c/0x8a0 > rcu_core+0x60c/0xc14 > rcu_core_si+0x14/0x24 > __do_softirq+0x19c/0x68c > irq_exit+0x118/0x2dc > handle_domain_irq+0xcc/0x134 > gic_handle_irq+0x7c/0x1bc > call_on_irq_stack+0x40/0x70 > do_interrupt_handler+0x78/0x9c > el1_interrupt+0x34/0x60 > el1h_64_irq_handler+0x1c/0x2c > el1h_64_irq+0x78/0x7c > _raw_spin_unlock_irqrestore+0x40/0xcc > sched_fork+0x4f0/0xb00 > copy_process+0xacc/0x3648 > kernel_clone+0x168/0x534 > kernel_thread+0x13c/0x1b0 > kthreadd+0x2bc/0x400 > ret_from_fork+0x10/0x20 > > Memory state around the buggy address: > ffff8000100b8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ffff8000100b8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > >ffff8000100b9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ^ > ffff8000100b9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ffff8000100b9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ==================================================================
Thanks, I'll take this via the arm64 tree as we're the only use of SCS.
One thing for future:
> Suggested-by: Kuan-Ying Lee <kuan-ying.lee@mediatek.com> > Reviewd-by: Will Deacon <will@kernel.org>
I gave an "Acked-by" and a "Tested-by" at [1], so those are the tags you should be using. Please don't convert them into a "Reviewed-by".
> Reviewd-by: Sami Tolvanen <samitolvanen@google.com>
This should be "Reviewed-by" (you have a typo).
Anyway, I'll fix these locally, no need to resend this time.
Will
[1] https://lore.kernel.org/r/20210929115447.GA21631@willie-the-truck
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