[PATCH] 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 | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/sound/soc/codecs/lpass-tx-macro.c b/sound/soc/codecs/lpass-tx-macro.c
index da6fcf7f0991..6575b0bb6a47 100644
--- a/sound/soc/codecs/lpass-tx-macro.c
+++ b/sound/soc/codecs/lpass-tx-macro.c
@@ -746,6 +746,10 @@ 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 < 0 && val > 15) {
+		dev_err(component->dev, "Wrong value for DMIC configuration");
+		return -EINVAL;
+	}
 
 	switch (e->reg) {
 	case CDC_TX_INP_MUX_ADC_MUX0_CFG0:
@@ -772,6 +776,9 @@ 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) {
@@ -785,13 +792,19 @@ static int tx_macro_put_dec_enum(struct snd_kcontrol *kcontrol,
 			snd_soc_component_write_field(component, mic_sel_reg,
 						      CDC_TXn_ADC_DMIC_SEL_MASK, 1);
 			dmic = TX_ADC_TO_DMIC(val);
-			dmic_clk_reg = CDC_TX_TOP_CSR_SWR_DMICn_CTL(dmic);
-			snd_soc_component_write_field(component, dmic_clk_reg,
-						CDC_TX_SWR_DMIC_CLK_SEL_MASK,
-						tx->dmic_clk_div);
+			if (dmic < 4) {
+				dmic_clk_reg = CDC_TX_TOP_CSR_SWR_DMICn_CTL(dmic);
+				snd_soc_component_write_field(component, dmic_clk_reg,
+							      CDC_TX_SWR_DMIC_CLK_SEL_MASK,
+								tx->dmic_clk_div);
+			} else {
+				dev_err(component->dev, "dmic for clk sel is wrong,
+					expected less than 4 but received %d\n", dmic);
+				return -EINVAL;
+			}
+
 		}
 	}
-
 	return snd_soc_dapm_put_enum_double(kcontrol, ucontrol);
 }
 
-- 
2.17.1