[PATCH v2] ASoC:codecs: lpass: Fix for KASAN use_after_free out of bounds

[Ravulapati Vishnu Vardhan Rao]

When we run syzkaller we get below Out of Bounds error.

"KASAN: slab-out-of-bounds Read in regcache_flat_read"

Below is the backtrace of the issue:

BUG: KASAN: slab-out-of-bounds in regcache_flat_read+0x10c/0x110
Read of size 4 at addr ffffff8088fbf714 by task syz-executor.4/14144
CPU: 6 PID: 14144 Comm: syz-executor.4 Tainted: G        W
Hardware name: Qualcomm Technologies, Inc. sc7280 CRD platform (rev5+) (DT)
Call trace:
dump_backtrace+0x0/0x4ec
show_stack+0x34/0x50
dump_stack_lvl+0xdc/0x11c
print_address_description+0x30/0x2d8
kasan_report+0x178/0x1e4
__asan_report_load4_noabort+0x44/0x50
regcache_flat_read+0x10c/0x110
regcache_read+0xf8/0x5a0
_regmap_read+0x45c/0x86c
_regmap_update_bits+0x128/0x290
regmap_update_bits_base+0xc0/0x15c
snd_soc_component_update_bits+0xa8/0x22c
snd_soc_component_write_field+0x68/0xd4
tx_macro_put_dec_enum+0x1d0/0x268
snd_ctl_elem_write+0x288/0x474

By Error checking and checking valid values issue gets rectifies.

Signed-off-by: Ravulapati Vishnu Vardhan Rao <quic_visr@xxxxxxxxxxx>
---
 sound/soc/codecs/lpass-tx-macro.c | 5 +++++
 1 file changed, 5 insertions(+)

Changes Since v1:
    
    - Check value with enum item value getting from control.
    - Removing of previously added code which is unwanted as already we get
      out with -EINVAL if value is out of bound.

diff --git a/sound/soc/codecs/lpass-tx-macro.c b/sound/soc/codecs/lpass-tx-macro.c
index da6fcf7f0991..de978c3d70b7 100644
--- a/sound/soc/codecs/lpass-tx-macro.c
+++ b/sound/soc/codecs/lpass-tx-macro.c
@@ -746,6 +746,8 @@ static int tx_macro_put_dec_enum(struct snd_kcontrol *kcontrol,
 	struct tx_macro *tx = snd_soc_component_get_drvdata(component);
 
 	val = ucontrol->value.enumerated.item[0];
+	if (val >= e->items)
+		return -EINVAL;
 
 	switch (e->reg) {
 	case CDC_TX_INP_MUX_ADC_MUX0_CFG0:
@@ -772,6 +774,9 @@ static int tx_macro_put_dec_enum(struct snd_kcontrol *kcontrol,
 	case CDC_TX_INP_MUX_ADC_MUX7_CFG0:
 		mic_sel_reg = CDC_TX7_TX_PATH_CFG0;
 		break;
+	default:
+		dev_err(component->dev, "Error in configuration!!\n");
+		return -EINVAL;
 	}
 
 	if (val != 0) {
-- 
2.17.1