[PATCH] kmsg: Use vmalloc instead of kmalloc when writing

[Sasha Levin <levinsasha928@gmail.com>]

There are no size checks in kmsg_write(), and we try allocating enough
memory to store everything userspace gave us, which may be too much for
kmalloc to allocate.

One option would be to limit it to something, but we can't come up with
a number that would make sense.

Instead, just use vmalloc so that nothing would break with large amounts
of data.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 drivers/char/mem.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index d6e9d08..e047783 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -815,7 +815,7 @@ static ssize_t kmsg_writev(struct kiocb *iocb, const struct iovec *iv,
 	ssize_t ret = -EFAULT;
 	size_t len = iov_length(iv, count);
 
-	line = kmalloc(len + 1, GFP_KERNEL);
+	line = vmalloc(len + 1);
 	if (line == NULL)
 		return -ENOMEM;
 
@@ -836,7 +836,7 @@ static ssize_t kmsg_writev(struct kiocb *iocb, const struct iovec *iv,
 	if (ret > len)
 		ret = len;
 out:
-	kfree(line);
+	vfree(line);
 	return ret;
 }
 
-- 
1.7.8.4