linux-kernel - [PATCH] char: raw: do not leak CONFIG_MAX_RAW

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Date:   Wed, 17 Jun 2020 17:33:13 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Rich Felker <dalias@...c.org>, Sam Ravnborg <sam@...nborg.org>,
        Siddharth Gupta <sidgup@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] char: raw: do not leak CONFIG_MAX_RAW_DEVS to userspace

include/uapi/linux/raw.h leaks CONFIG_MAX_RAW_DEVS to userspace.

Userspace programs cannot use MAX_RAW_MINORS since CONFIG_MAX_RAW_DEVS
is not available anyway.

Remove the MAX_RAW_MINORS definition from the exported header, and use
CONFIG_MAX_RAW_DEVS in drivers/char/raw.c

While I was here, I converted printk(KERN_WARNING ...) to pr_warn(...)
and stretched the warning message.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 drivers/char/raw.c         | 8 ++++----
 include/uapi/linux/raw.h   | 2 --
 scripts/headers_install.sh | 1 -
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/char/raw.c b/drivers/char/raw.c
index 3484e9145aea..380bf518338e 100644
--- a/drivers/char/raw.c
+++ b/drivers/char/raw.c
@@ -37,7 +37,7 @@ static struct raw_device_data *raw_devices;
 static DEFINE_MUTEX(raw_mutex);
 static const struct file_operations raw_ctl_fops; /* forward declaration */
 
-static int max_raw_minors = MAX_RAW_MINORS;
+static int max_raw_minors = CONFIG_MAX_RAW_DEVS;
 
 module_param(max_raw_minors, int, 0);
 MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
@@ -317,9 +317,9 @@ static int __init raw_init(void)
 	int ret;
 
 	if (max_raw_minors < 1 || max_raw_minors > 65536) {
-		printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
-			" between 1 and 65536), using %d\n", MAX_RAW_MINORS);
-		max_raw_minors = MAX_RAW_MINORS;
+		pr_warn("raw: invalid max_raw_minors (must be between 1 and 65536), using %d\n",
+			CONFIG_MAX_RAW_DEVS);
+		max_raw_minors = CONFIG_MAX_RAW_DEVS;
 	}
 
 	raw_devices = vzalloc(array_size(max_raw_minors,
diff --git a/include/uapi/linux/raw.h b/include/uapi/linux/raw.h
index dc96dda479d6..47874919d0b9 100644
--- a/include/uapi/linux/raw.h
+++ b/include/uapi/linux/raw.h
@@ -14,6 +14,4 @@ struct raw_config_request
 	__u64	block_minor;
 };
 
-#define MAX_RAW_MINORS CONFIG_MAX_RAW_DEVS
-
 #endif /* __LINUX_RAW_H */
diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh
index 955cf3aedf21..84f89ff6efdd 100755
--- a/scripts/headers_install.sh
+++ b/scripts/headers_install.sh
@@ -90,7 +90,6 @@ include/uapi/linux/elfcore.h:CONFIG_BINFMT_ELF_FDPIC
 include/uapi/linux/eventpoll.h:CONFIG_PM_SLEEP
 include/uapi/linux/hw_breakpoint.h:CONFIG_HAVE_MIXED_BREAKPOINTS_REGS
 include/uapi/linux/pktcdvd.h:CONFIG_CDROM_PKTCDVD_WCACHE
-include/uapi/linux/raw.h:CONFIG_MAX_RAW_DEVS
 "
 
 for c in $configs
-- 
2.25.1