Commit b011946d authored by Yi Yang's avatar Yi Yang Committed by Max Filippov
Browse files

xtensa/simdisk: fix proc_read_simdisk() 



The commit a69755b1 ("xtensa simdisk: switch to proc_create_data()")
split read operation into two parts, first retrieving the path when it's
non-null and second retrieving the trailing '\n'. However when the path
is non-null the first simple_read_from_buffer updates ppos, and the
second simple_read_from_buffer returns 0 if ppos is greater than 1 (i.e.
almost always). As a result reading from that proc file is almost always
empty.

Fix it by making a temporary copy of the path with the trailing '\n' and
using simple_read_from_buffer on that copy.

Cc: stable@vger.kernel.org
Fixes: a69755b1 ("xtensa simdisk: switch to proc_create_data()")
Signed-off-by: default avatarYi Yang <yiyang13@huawei.com>
Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent c6ab42b3

arch/xtensa/platforms/iss/simdisk.c

+12 −6
Original line number Diff line number Diff line
@@ -211,12 +211,18 @@ static ssize_t proc_read_simdisk(struct file *file, char __user *buf, 
	struct simdisk *dev = pde_data(file_inode(file));

	const char *s = dev->filename;

	if (s) {

		ssize_t n = simple_read_from_buffer(buf, size, ppos,

							s, strlen(s));

		if (n < 0)

			return n;

		buf += n;

		size -= n;

		ssize_t len = strlen(s);

		char *temp = kmalloc(len + 2, GFP_KERNEL);



		if (!temp)

			return -ENOMEM;



		len = scnprintf(temp, len + 2, "%s\n", s);

		len = simple_read_from_buffer(buf, size, ppos,

					      temp, len);



		kfree(temp);

		return len;

	}

	return simple_read_from_buffer(buf, size, ppos, "\n", 1);

}