[v1] soc: qcom: qmi_encdec: Restrict string length in decode

[PATCH] soc: qcom: qmi_encdec: Restrict string length in decode

Posted by Praveenkumar I 2 years, 6 months ago

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

Re: [PATCH] soc: qcom: qmi_encdec: Restrict string length in decode

Posted by Konrad Dybcio 2 years, 6 months ago

On 31.07.2023 11:14, Praveenkumar I wrote:
> 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>
> ---
Fixes + Cc: stable?

Konrad

Re: [PATCH] soc: qcom: qmi_encdec: Restrict string length in decode

Posted by Praveenkumar I 2 years, 6 months ago

On 7/31/2023 2:48 PM, Konrad Dybcio wrote:
> On 31.07.2023 11:14, Praveenkumar I wrote:
>> 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>
>> ---
> Fixes + Cc: stable?
Sure, will add.
>
> Konrad
--
Thanks,
Praveenkumar