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@vger.kernel.org Signed-off-by: Nick Desaulniers nick.desaulniers@gmail.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.