[PATCH] Potential null pointer dereference in amiga serial driver

A pointer is dereferenced before it is null-checked.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 1dc4259213a6..777bc499bbbd 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -861,13 +861,18 @@ static void change_speed(struct async_struct *info,
 
 static void rs_put_char(struct tty_struct *tty, unsigned char ch)
 {
-        struct async_struct *info = (struct async_struct *)tty->driver_data;
+        struct async_struct *info;
         unsigned long flags;
 
+        if (!tty)
+                return;
+
+        info = tty->driver_data;
+
         if (serial_paranoia_check(info, tty->name, "rs_put_char"))
                 return;
 
-        if (!tty || !info->xmit.buf)
+        if (!info->xmit.buf)
                 return;
 
         local_irq_save(flags);
@@ -910,13 +915,18 @@ static void rs_flush_chars(struct tty_struct *tty)
 static int rs_write(struct tty_struct * tty, const unsigned char *buf, int count)
 {
         int     c, ret = 0;
-        struct async_struct *info = (struct async_struct *)tty->driver_data;
+        struct async_struct *info;
         unsigned long flags;
 
+        if (!tty)
+                return 0;
+
+        info = tty->driver_data;
+
         if (serial_paranoia_check(info, tty->name, "rs_write"))
                 return 0;
 
-        if (!tty || !info->xmit.buf || !tmp_buf)
+        if (!info->xmit.buf || !tmp_buf)
                 return 0;
 
         local_save_flags(flags);