[PATCH] char/lp: convert to y2038 safe - Y2038

4 Dec 2015

The y2038 issue of printer exist in the time_t of timeval in ioctl
LPSETTIME. This patch try to convert it to y2038 safe by the
following steps:
1.  Remove timeval from lp_set_timeout in order to support 32bit and
    64bit time_t in the same function without the new definition
    of timeval64 or something else.
2.  Handle both 32bit and 64bit time in the same LPSETTIMEOUT switch
    case in order to support y2038 safe and non-safe cases.
3.  Merge compat of LPSETTIMEOUT into non-comapt one.
I thought split these steps into three different patches. But I feel
these changes are simple and direct.
Signed-off-by: Bamvor Jian Zhang bamvor.zhangjian@linaro.org
---
 drivers/char/lp.c | 94 ++++++++++++++++++++++++++++++-------------------------
 1 file changed, 52 insertions(+), 42 deletions(-)

diff --git a/drivers/char/lp.c b/drivers/char/lp.c
index c4094c4..a207e0c 100644
--- a/drivers/char/lp.c
+++ b/drivers/char/lp.c
@@ -136,6 +136,14 @@
 #include <asm/irq.h>
 #include <asm/uaccess.h>
+/*
+ * FIXME: It should be removed after COMPAT_USE_64BIT_TIME is accessible for
+ * 32bit architecture.
+ */
+#ifndef COMPAT_USE_64BIT_TIME
+#define COMPAT_USE_64BIT_TIME (0)
+#endif /* COMPAT_USE_64BIT_TIME */
+
 /* if you have more than 8 printers, remember to increase LP_NO */
 #define LP_NO 8
@@ -572,6 +580,22 @@ static int lp_release(struct inode * inode, struct file * file)
    return 0;
 }
+static int lp_set_timeout(unsigned int minor, s64 tv_sec, s64 tv_usec)
+{
+	long to_jiffies;
+
+	if ((tv_sec < 0) || (tv_usec < 0))
+		return -EINVAL;
+
+	to_jiffies = usecs_to_jiffies(tv_usec);
+	to_jiffies += tv_sec * (long)HZ;
+	if (to_jiffies <= 0)
+		return -EINVAL;
+
+	lp_table[minor].timeout = to_jiffies;
+	return 0;
+}
+
 static int lp_do_ioctl(unsigned int minor, unsigned int cmd,
    unsigned long arg, void __user *argp)
 {
@@ -586,6 +610,9 @@ static int lp_do_ioctl(unsigned int minor, unsigned int cmd,
    if ((LP_F(minor) & LP_EXIST) == 0)
    	return -ENODEV;
    switch ( cmd ) {
+		s32 time32[2];
+		s64 time64[2];
+
    	case LPTIME:
    		if (arg > UINT_MAX / HZ)
    			return -EINVAL;
@@ -647,58 +674,49 @@ static int lp_do_ioctl(unsigned int minor, unsigned int cmd,
    					sizeof(struct lp_stats));
    		break;
 #endif
- 		case LPGETFLAGS:
- 			status = LP_F(minor);
+		case LPGETFLAGS:
+			status = LP_F(minor);
    		if (copy_to_user(argp, &status, sizeof(int)))
    			return -EFAULT;
    		break;
+		case LPSETTIMEOUT:
+			/*
+			 * For 64bit application or 32bit application with 64bit
+			 * time_t
+			 */
+			if ((IS_ENABLED(CONFIG_64BIT) && !is_compat_task())
+			    || COMPAT_USE_64BIT_TIME) {
+				if (copy_from_user(time64, argp,
+							sizeof(time64)))
+					return -EFAULT;
+
+				return lp_set_timeout(minor, time64[0],
+						time64[1]);
+			} else {
+				if (copy_from_user(time32, argp,
+							sizeof(time32)))
+					return -EFAULT;
+
+				return lp_set_timeout(minor, time32[0],
+						time32[1]);
+			}
+			break;
    	default:
    		retval = -EINVAL;
    }
    return retval;
 }
-static int lp_set_timeout(unsigned int minor, struct timeval *par_timeout)
-{
-	long to_jiffies;
-
-	/* Convert to jiffies, place in lp_table */
-	if ((par_timeout->tv_sec < 0) ||
-	    (par_timeout->tv_usec < 0)) {
-		return -EINVAL;
-	}
-	to_jiffies = DIV_ROUND_UP(par_timeout->tv_usec, 1000000/HZ);
-	to_jiffies += par_timeout->tv_sec * (long) HZ;
-	if (to_jiffies <= 0) {
-		return -EINVAL;
-	}
-	lp_table[minor].timeout = to_jiffies;
-	return 0;
-}
-
 static long lp_ioctl(struct file *file, unsigned int cmd,
    		unsigned long arg)
 {
    unsigned int minor;
-	struct timeval par_timeout;
    int ret;
minor = iminor(file_inode(file));
    mutex_lock(&lp_mutex);
-	switch (cmd) {
-	case LPSETTIMEOUT:
-		if (copy_from_user(&par_timeout, (void __user *)arg,
-					sizeof (struct timeval))) {
-			ret = -EFAULT;
-			break;
-		}
-		ret = lp_set_timeout(minor, &par_timeout);
-		break;
-	default:
-		ret = lp_do_ioctl(minor, cmd, arg, (void __user *)arg);
-		break;
-	}
+	ret = lp_do_ioctl(minor, cmd, arg, (void __user *)arg);
    mutex_unlock(&lp_mutex);
return ret;
@@ -709,19 +727,11 @@ static long lp_compat_ioctl(struct file *file, unsigned int cmd,
    		unsigned long arg)
 {
    unsigned int minor;
-	struct timeval par_timeout;
    int ret;
minor = iminor(file_inode(file));
    mutex_lock(&lp_mutex);
    switch (cmd) {
-	case LPSETTIMEOUT:
-		if (compat_get_timeval(&par_timeout, compat_ptr(arg))) {
-			ret = -EFAULT;
-			break;
-		}
-		ret = lp_set_timeout(minor, &par_timeout);
-		break;
 #ifdef LP_STATS
    case LPGETSTATS:
    	/* FIXME: add an implementation if you set LP_STATS */
-- 
2.1.4


    