[PATCH 5.10 331/406] soc: qcom: qmi_encdec: Restrict string length in decode

Greg Kroah-Hartman
2023-09-17T19:39:08Z

From: Chris Lew <quic_clew@quicinc.com>

commit 8d207400fd6b79c92aeb2f33bb79f62dff904ea2 upstream.

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.

Fixes: 9b8a11e82615 ("soc: qcom: Introduce QMI encoder/decoder")
Cc: stable@vger.kernel.org
Signed-off-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Praveenkumar I <quic_ipkumar@quicinc.com>
Link: https://lore.kernel.org/r/20230801064712.3590128-1-quic_ipkumar@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/soc/qcom/qmi_encdec.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/soc/qcom/qmi_encdec.c
+++ b/drivers/soc/qcom/qmi_encdec.c
@@ -534,8 +534,8 @@ static int qmi_decode_string_elem(struct
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) {