Messages in this thread | | | Subject | Re: [PATCH v2] scs: Release kasan vmalloc poison in scs_free process | From | Yee Lee <> | Date | Thu, 30 Sep 2021 17:06:53 +0800 |
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Got it. Thank you.
Yee
On Thu, 2021-09-30 at 09:35 +0100, Will Deacon wrote: > 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://urldefense.com/v3/__https://lore.kernel.org/r/20210929115447.GA21631@willie-the-truck__;!!CTRNKA9wMg0ARbw!yjJi1VvoIbI7CZQJplT_jdN087Pkk6pzXAZ12_FpegZzaUEQutkzBjX85rub_NI$ >
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