linux-kernel - [PATCH] usbip: tools: fix atoi() on non-null terminated string

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Message-Id: <20181016180343.5620-1-colin.king@canonical.com>
Date:   Tue, 16 Oct 2018 19:03:43 +0100
From:   Colin King <colin.king@...onical.com>
To:     Valentina Manea <valentina.manea.m@...il.com>,
        Shuah Khan <shuah@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] usbip: tools: fix atoi() on non-null terminated string

From: Colin Ian King <colin.king@...onical.com>

Currently the call to atoi is being passed a single char string
that is not null terminated, so there is a potential read overrun
along the stack when parsing for an integer value.  Fix this by
instead using a 2 char string that is initialized to all zeros
to ensure that a 1 char read into the string is always terminated
with a \0.

Detected by cppcheck:
"Invalid atoi() argument nr 1. A nul-terminated string is required."

Fixes: 3391ba0e2792 ("usbip: tools: Extract generic code to be shared with vudc backend")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 tools/usb/usbip/libsrc/usbip_host_common.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/usb/usbip/libsrc/usbip_host_common.c b/tools/usb/usbip/libsrc/usbip_host_common.c
index dc93fadbee96..d79c7581b175 100644
--- a/tools/usb/usbip/libsrc/usbip_host_common.c
+++ b/tools/usb/usbip/libsrc/usbip_host_common.c
@@ -43,7 +43,7 @@ static int32_t read_attr_usbip_status(struct usbip_usb_device *udev)
 	int size;
 	int fd;
 	int length;
-	char status;
+	char status[2] = { 0 };
 	int value = 0;
 
 	size = snprintf(status_attr_path, sizeof(status_attr_path),
@@ -61,14 +61,14 @@ static int32_t read_attr_usbip_status(struct usbip_usb_device *udev)
 		return -1;
 	}
 
-	length = read(fd, &status, 1);
+	length = read(fd, status, 1);
 	if (length < 0) {
 		err("error reading attribute %s", status_attr_path);
 		close(fd);
 		return -1;
 	}
 
-	value = atoi(&status);
+	value = atoi(status);
 
 	return value;
 }
-- 
2.19.1