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From:   Praveenkumar I <quic_ipkumar@quicinc.com>
To:     <agross@kernel.org>, <andersson@kernel.org>,
        <konrad.dybcio@linaro.org>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     <quic_varada@quicinc.com>, <quic_clew@quicinc.com>
Subject: [PATCH] soc: qcom: qmi_encdec: Restrict string length in decode
Date:   Mon, 31 Jul 2023 14:44:08 +0530
Message-ID: <20230731091408.2458199-1-quic_ipkumar@quicinc.com>
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The QMI TLV value for strings in a lot of qmi element info structures
account for null terminated strings with MAX_LEN + 1. If a string is
actually MAX_LEN + 1 length, this will cause an out of bounds access
when the NULL character is appended in decoding.

Signed-off-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Praveenkumar I <quic_ipkumar@quicinc.com>
---
 drivers/soc/qcom/qmi_encdec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/qmi_encdec.c b/drivers/soc/qcom/qmi_encdec.c
index b7158e3c3a0b..5c7161b18b72 100644
--- a/drivers/soc/qcom/qmi_encdec.c
+++ b/drivers/soc/qcom/qmi_encdec.c
@@ -534,8 +534,8 @@ static int qmi_decode_string_elem(const struct qmi_elem_info *ei_array,
 		decoded_bytes += rc;
 	}
 
-	if (string_len > temp_ei->elem_len) {
-		pr_err("%s: String len %d > Max Len %d\n",
+	if (string_len >= temp_ei->elem_len) {
+		pr_err("%s: String len %d >= Max Len %d\n",
 		       __func__, string_len, temp_ei->elem_len);
 		return -ETOOSMALL;
 	} else if (string_len > tlv_len) {
-- 
2.34.1