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Date: Thu, 18 Jan 2018 11:38:46 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Nick Desaulniers <nick.desaulniers@...il.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>,
Alexander Potapenko <glider@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
usacrc@...oo.com, stable@...r.kernel.org,
Benjamin Tissoires <benjamin.tissoires@...hat.com>,
Nick Dyer <nick@...anahar.org>,
Andrew Duggan <aduggan@...aptics.com>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Guenter Roeck <linux@...ck-us.net>,
linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: synaptics-rmi4 - prevent UAF reported by KASAN
On Tue, Jan 16, 2018 at 10:25:01PM -0800, Nick Desaulniers wrote:
> KASAN found a UAF due to dangling pointer. As the report below says,
> rmi_f11_attention() accesses drvdata->attn_data.data, which was freed in
> rmi_irq_fn.
>
> [ 311.424062] BUG: KASAN: use-after-free in
> rmi_f11_attention+0x526/0x5e0 [rmi_core]
> [ 311.424067] Read of size 27 at addr ffff88041fd610db by task
> irq/131-i2c_hid/1162
>
> [ 311.424075] CPU: 0 PID: 1162 Comm: irq/131-i2c_hid Not tainted
> 4.15.0-rc8+ #2
> [ 311.424076] Hardware name: Razer Blade Stealth/Razer, BIOS 6.05
> 01/26/2017
> [ 311.424078] Call Trace:
> [ 311.424086] dump_stack+0xae/0x12d
> [ 311.424090] ? _atomic_dec_and_lock+0x103/0x103
> [ 311.424094] ? show_regs_print_info+0xa/0xa
> [ 311.424099] ? input_handle_event+0x10b/0x810
> [ 311.424104] print_address_description+0x65/0x229
> [ 311.424108] kasan_report.cold.5+0xa7/0x281
> [ 311.424117] rmi_f11_attention+0x526/0x5e0 [rmi_core]
> [ 311.424123] ? memcpy+0x1f/0x50
> [ 311.424132] ? rmi_f11_attention+0x526/0x5e0 [rmi_core]
> [ 311.424143] ? rmi_f11_probe+0x1e20/0x1e20 [rmi_core]
> [ 311.424153] ? rmi_process_interrupt_requests+0x220/0x2a0 [rmi_core]
> [ 311.424163] ? rmi_irq_fn+0x22c/0x270 [rmi_core]
> [ 311.424173] ? rmi_process_interrupt_requests+0x2a0/0x2a0 [rmi_core]
> [ 311.424177] ? free_irq+0xa0/0xa0
> [ 311.424180] ? irq_finalize_oneshot.part.39+0xeb/0x180
> [ 311.424190] ? rmi_process_interrupt_requests+0x2a0/0x2a0 [rmi_core]
> [ 311.424193] ? irq_thread_fn+0x3d/0x80
> [ 311.424197] ? irq_finalize_oneshot.part.39+0x180/0x180
> [ 311.424200] ? irq_thread+0x21d/0x290
> [ 311.424203] ? irq_thread_check_affinity+0x170/0x170
> [ 311.424207] ? remove_wait_queue+0x150/0x150
> [ 311.424212] ? kasan_unpoison_shadow+0x30/0x40
> [ 311.424214] ? __init_waitqueue_head+0xa0/0xd0
> [ 311.424218] ? task_non_contending.cold.55+0x18/0x18
> [ 311.424221] ? irq_forced_thread_fn+0xa0/0xa0
> [ 311.424226] ? irq_thread_check_affinity+0x170/0x170
> [ 311.424230] ? kthread+0x19e/0x1c0
> [ 311.424233] ? kthread_create_worker_on_cpu+0xc0/0xc0
> [ 311.424237] ? ret_from_fork+0x32/0x40
>
> [ 311.424244] Allocated by task 899:
> [ 311.424249] kasan_kmalloc+0xbf/0xe0
> [ 311.424252] __kmalloc_track_caller+0xd9/0x1f0
> [ 311.424255] kmemdup+0x17/0x40
> [ 311.424264] rmi_set_attn_data+0xa4/0x1b0 [rmi_core]
> [ 311.424269] rmi_raw_event+0x10b/0x1f0 [hid_rmi]
> [ 311.424278] hid_input_report+0x1a8/0x2c0 [hid]
> [ 311.424283] i2c_hid_irq+0x146/0x1d0 [i2c_hid]
> [ 311.424286] irq_thread_fn+0x3d/0x80
> [ 311.424288] irq_thread+0x21d/0x290
> [ 311.424291] kthread+0x19e/0x1c0
> [ 311.424293] ret_from_fork+0x32/0x40
>
> [ 311.424296] Freed by task 1162:
> [ 311.424300] kasan_slab_free+0x71/0xc0
> [ 311.424303] kfree+0x90/0x190
> [ 311.424311] rmi_irq_fn+0x1b2/0x270 [rmi_core]
> [ 311.424319] rmi_irq_fn+0x257/0x270 [rmi_core]
> [ 311.424322] irq_thread_fn+0x3d/0x80
> [ 311.424324] irq_thread+0x21d/0x290
> [ 311.424327] kthread+0x19e/0x1c0
> [ 311.424330] ret_from_fork+0x32/0x40
>
> [ 311.424334] The buggy address belongs to the object at
> ffff88041fd610c0
> which belongs to the cache kmalloc-64 of size 64
> [ 311.424340] The buggy address is located 27 bytes inside of
> 64-byte region [ffff88041fd610c0, ffff88041fd61100)
> [ 311.424344] The buggy address belongs to the page:
> [ 311.424348] page:ffffea00107f5840 count:1 mapcount:0 mapping:
> (null) index:0x0
> [ 311.424353] flags: 0x17ffffc0000100(slab)
> [ 311.424358] raw: 0017ffffc0000100 0000000000000000 0000000000000000
> 00000001802a002a
> [ 311.424363] raw: dead000000000100 dead000000000200 ffff8804228036c0
> 0000000000000000
> [ 311.424366] page dumped because: kasan: bad access detected
>
> [ 311.424369] Memory state around the buggy address:
> [ 311.424373] ffff88041fd60f80: 00 00 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00
> [ 311.424377] ffff88041fd61000: fb fb fb fb fb fb fb fb fc fc fc fc
> fb fb fb fb
> [ 311.424381] >ffff88041fd61080: fb fb fb fb fc fc fc fc fb fb fb fb
> fb fb fb fb
> [ 311.424384] ^
> [ 311.424387] ffff88041fd61100: fc fc fc fc fb fb fb fb fb fb fb fb
> fc fc fc fc
> [ 311.424391] ffff88041fd61180: fb fb fb fb fb fb fb fb fc fc fc fc
> fb fb fb fb
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Nick Desaulniers <nick.desaulniers@...il.com>
> ---
> drivers/input/rmi4/rmi_driver.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
> index 4f2bb59..141ea22 100644
> --- a/drivers/input/rmi4/rmi_driver.c
> +++ b/drivers/input/rmi4/rmi_driver.c
> @@ -230,8 +230,10 @@ static irqreturn_t rmi_irq_fn(int irq, void *dev_id)
> rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
> "Failed to process interrupt request: %d\n", ret);
>
> - if (count)
> + if (count) {
> kfree(attn_data.data);
> + attn_data.data = NULL;
> + }
>
> if (!kfifo_is_empty(&drvdata->attn_fifo))
> return rmi_irq_fn(irq, dev_id);
Ugh, this code needs reworking as we really do not want recursion in an
interrupt handler. Anyway, this will suffice for stable; applied, thank
you.
--
Dmitry
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