linux-kernel - [PATCH 20/20] s390/watchdog: Manual replacement of the deprecated strlcpy() with return values

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210222151231.22572-21-romain.perier@gmail.com>
Date:   Mon, 22 Feb 2021 16:12:31 +0100
From:   Romain Perier <romain.perier@...il.com>
To:     Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     Romain Perier <romain.perier@...il.com>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 20/20] s390/watchdog: Manual replacement of the deprecated strlcpy() with return values

The strlcpy() reads the entire source buffer first, it is dangerous if
the source buffer lenght is unbounded or possibility non NULL-terminated.
It can lead to linear read overflows, crashes, etc...

As recommended in the deprecated interfaces [1], it should be replaced
by strscpy.

This commit replaces all calls to strlcpy that handle the return values
by the corresponding strscpy calls with new handling of the return
values (as it is quite different between the two functions).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy

Signed-off-by: Romain Perier <romain.perier@...il.com>
---
 drivers/watchdog/diag288_wdt.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/diag288_wdt.c b/drivers/watchdog/diag288_wdt.c
index aafc8d98bf9f..5703f35dd0b7 100644
--- a/drivers/watchdog/diag288_wdt.c
+++ b/drivers/watchdog/diag288_wdt.c
@@ -111,7 +111,7 @@ static unsigned long wdt_status;
 static int wdt_start(struct watchdog_device *dev)
 {
 	char *ebc_cmd;
-	size_t len;
+	ssize_t len;
 	int ret;
 	unsigned int func;
 
@@ -126,7 +126,9 @@ static int wdt_start(struct watchdog_device *dev)
 			clear_bit(DIAG_WDOG_BUSY, &wdt_status);
 			return -ENOMEM;
 		}
-		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
+		len = strscpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
+		if (len == -E2BIG)
+			return -E2BIG;
 		ASCEBC(ebc_cmd, MAX_CMDLEN);
 		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
 
@@ -163,7 +165,7 @@ static int wdt_stop(struct watchdog_device *dev)
 static int wdt_ping(struct watchdog_device *dev)
 {
 	char *ebc_cmd;
-	size_t len;
+	ssize_t len;
 	int ret;
 	unsigned int func;
 
@@ -173,7 +175,9 @@ static int wdt_ping(struct watchdog_device *dev)
 		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 		if (!ebc_cmd)
 			return -ENOMEM;
-		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
+		len = strscpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
+		if (len == -E2BIG)
+			return -E2BIG;
 		ASCEBC(ebc_cmd, MAX_CMDLEN);
 		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);