[PATCH 4.6 174/203] ALSA: hda - fix read before array start

Greg Kroah-Hartman
2016-07-25T21:53:24Z

From: Bob Copeland <me@bobcopeland.com>

commit 81e43960dce1c8e58e682fb3ec26c1d8f83a9afc upstream.

UBSAN reports the following warning from accessing path->path[-1]
in set_path_power():

[ 16.078040] ================================================================================
[ 16.078124] UBSAN: Undefined behaviour in sound/pci/hda/hda_generic.c:3981:17
[ 16.078198] index -1 is out of range for type 'hda_nid_t [10]'
[ 16.078270] CPU: 2 PID: 1738 Comm: modprobe Not tainted 4.7.0-rc1-wt+ #47
[ 16.078274] Hardware name: LENOVO 3443CTO/3443CTO, BIOS G6ET23WW (1.02 ) 08/14/2012
[ 16.078278] ffff8800cb246000 ffff8800cb3638b8 ffffffff815c4fe3 0000000000000032
[ 16.078286] ffff8800cb3638e0 ffffffffffffffff ffff8800cb3638d0 ffffffff8162443d
[ 16.078294] ffffffffa0894200 ffff8800cb363920 ffffffff81624af7 0000000000000292
[ 16.078302] Call Trace:
[ 16.078311] [<ffffffff815c4fe3>] dump_stack+0x86/0xd3
[ 16.078317] [<ffffffff8162443d>] ubsan_epilogue+0xd/0x40
[ 16.078324] [<ffffffff81624af7>] __ubsan_handle_out_of_bounds+0x67/0x70
[ 16.078335] [<ffffffffa087665f>] set_path_power+0x1bf/0x230 [snd_hda_codec_generic]
[ 16.078344] [<ffffffffa087880d>] add_pin_power_ctls+0x8d/0xc0 [snd_hda_codec_generic]
[ 16.078352] [<ffffffffa087f190>] ? pin_power_down_callback+0x20/0x20 [snd_hda_codec_generic]
[ 16.078360] [<ffffffffa0878947>] add_all_pin_power_ctls+0x107/0x150 [snd_hda_codec_generic]
[ 16.078370] [<ffffffffa08842b3>] snd_hda_gen_parse_auto_config+0x2d73/0x49e0 [snd_hda_codec_generic]
[ 16.078376] [<ffffffff81173360>] ? trace_hardirqs_on_caller+0x1b0/0x2c0
[ 16.078390] [<ffffffffa089df27>] alc_parse_auto_config+0x147/0x310 [snd_hda_codec_realtek]
[ 16.078402] [<ffffffffa08a332a>] patch_alc269+0x23a/0x560 [snd_hda_codec_realtek]
[ 16.078417] [<ffffffffa0838644>] hda_codec_driver_probe+0xa4/0x1a0 [snd_hda_codec]
[ 16.078424] [<ffffffff817bbac1>] driver_probe_device+0x101/0x380
[ 16.078430] [<ffffffff817bbdf9>] __driver_attach+0xb9/0x100
[ 16.078438] [<ffffffff817bbd40>] ? driver_probe_device+0x380/0x380
[ 16.078444] [<ffffffff817b8d20>] bus_for_each_dev+0x70/0xc0
[ 16.078449] [<ffffffff817bb087>] driver_attach+0x27/0x50
[ 16.078454] [<ffffffff817ba956>] bus_add_driver+0x166/0x2c0
[ 16.078460] [<ffffffffa0369000>] ? 0xffffffffa0369000
[ 16.078465] [<ffffffff817bd13d>] driver_register+0x7d/0x130
[ 16.078477] [<ffffffffa083816f>] __hda_codec_driver_register+0x6f/0x90 [snd_hda_codec]
[ 16.078488] [<ffffffffa036901e>] realtek_driver_init+0x1e/0x1000 [snd_hda_codec_realtek]
[ 16.078493] [<ffffffff8100215e>] do_one_initcall+0x4e/0x1d0
[ 16.078499] [<ffffffff8119f54d>] ? rcu_read_lock_sched_held+0x6d/0x80
[ 16.078504] [<ffffffff813701b1>] ? kmem_cache_alloc_trace+0x391/0x560
[ 16.078510] [<ffffffff812bb314>] ? do_init_module+0x28/0x273
[ 16.078515] [<ffffffff812bb387>] do_init_module+0x9b/0x273
[ 16.078522] [<ffffffff811e3782>] load_module+0x20b2/0x3410
[ 16.078527] [<ffffffff811df140>] ? m_show+0x210/0x210
[ 16.078533] [<ffffffff813b2b26>] ? kernel_read+0x66/0xe0
[ 16.078541] [<ffffffff811e4cfa>] SYSC_finit_module+0xba/0xc0
[ 16.078547] [<ffffffff811e4d1e>] SyS_finit_module+0xe/0x10
[ 16.078552] [<ffffffff81a860fc>] entry_SYSCALL_64_fastpath+0x1f/0xbd
[ 16.078556] ================================================================================

Fix by checking path->depth before use.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/pci/hda/hda_generic.c | 2 ++
1 file changed, 2 insertions(+)

--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -3977,6 +3977,8 @@ static hda_nid_t set_path_power(struct h

for (n = 0; n < spec->paths.used; n++) {
path = snd_array_elem(&spec->paths, n);
+ if (!path->depth)
+ continue;
if (path->path[0] == nid ||
path->path[path->depth - 1] == nid) {
bool pin_old = path->pin_enabled;