From 81e43960dce1c8e58e682fb3ec26c1d8f83a9afc Mon Sep 17 00:00:00 2001 From: Bob Copeland Date: Sat, 25 Jun 2016 07:58:45 -0400 Subject: [PATCH] ALSA: hda - fix read before array start 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] [] dump_stack+0x86/0xd3 [ 16.078317] [] ubsan_epilogue+0xd/0x40 [ 16.078324] [] __ubsan_handle_out_of_bounds+0x67/0x70 [ 16.078335] [] set_path_power+0x1bf/0x230 [snd_hda_codec_generic] [ 16.078344] [] add_pin_power_ctls+0x8d/0xc0 [snd_hda_codec_generic] [ 16.078352] [] ? pin_power_down_callback+0x20/0x20 [snd_hda_codec_generic] [ 16.078360] [] add_all_pin_power_ctls+0x107/0x150 [snd_hda_codec_generic] [ 16.078370] [] snd_hda_gen_parse_auto_config+0x2d73/0x49e0 [snd_hda_codec_generic] [ 16.078376] [] ? trace_hardirqs_on_caller+0x1b0/0x2c0 [ 16.078390] [] alc_parse_auto_config+0x147/0x310 [snd_hda_codec_realtek] [ 16.078402] [] patch_alc269+0x23a/0x560 [snd_hda_codec_realtek] [ 16.078417] [] hda_codec_driver_probe+0xa4/0x1a0 [snd_hda_codec] [ 16.078424] [] driver_probe_device+0x101/0x380 [ 16.078430] [] __driver_attach+0xb9/0x100 [ 16.078438] [] ? driver_probe_device+0x380/0x380 [ 16.078444] [] bus_for_each_dev+0x70/0xc0 [ 16.078449] [] driver_attach+0x27/0x50 [ 16.078454] [] bus_add_driver+0x166/0x2c0 [ 16.078460] [] ? 0xffffffffa0369000 [ 16.078465] [] driver_register+0x7d/0x130 [ 16.078477] [] __hda_codec_driver_register+0x6f/0x90 [snd_hda_codec] [ 16.078488] [] realtek_driver_init+0x1e/0x1000 [snd_hda_codec_realtek] [ 16.078493] [] do_one_initcall+0x4e/0x1d0 [ 16.078499] [] ? rcu_read_lock_sched_held+0x6d/0x80 [ 16.078504] [] ? kmem_cache_alloc_trace+0x391/0x560 [ 16.078510] [] ? do_init_module+0x28/0x273 [ 16.078515] [] do_init_module+0x9b/0x273 [ 16.078522] [] load_module+0x20b2/0x3410 [ 16.078527] [] ? m_show+0x210/0x210 [ 16.078533] [] ? kernel_read+0x66/0xe0 [ 16.078541] [] SYSC_finit_module+0xba/0xc0 [ 16.078547] [] SyS_finit_module+0xe/0x10 [ 16.078552] [] entry_SYSCALL_64_fastpath+0x1f/0xbd [ 16.078556] ================================================================================ Fix by checking path->depth before use. Signed-off-by: Bob Copeland Cc: Signed-off-by: Takashi Iwai --- sound/pci/hda/hda_generic.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c index 320445f3bf73..79c7b340acc2 100644 --- 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 hda_codec *codec, hda_nid_t nid, 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; -- 2.20.1