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Commit a7503434 authored by Oleg Drokin's avatar Oleg Drokin Committed by Greg Kroah-Hartman
Browse files

staging/lustre/llite: fix ll_getname user buffer copy 

strncpy_from_user could return negative values on error,
so need to take those into account.
Since ll_getname is used to get a single component name from userspace
to transfer to server as-is, there's no need to allocate 4k buffer
as done by __getname. Allocate NAME_MAX+1 buffer instead to ensure
we have enough for a null terminated max valid length buffer.

This was discovered by Al Viro in https://lkml.org/lkml/2015/4/11/243



Signed-off-by: default avatarOleg Drokin <green@linuxhacker.ru>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d8bc89a7

drivers/staging/lustre/lustre/llite/dir.c

+13 −8
Original line number Diff line number Diff line
@@ -1213,29 +1213,34 @@ static int quotactl_ioctl(struct ll_sb_info *sbi, struct if_quotactl *qctl) 
	return rc;

}



static char *

ll_getname(const char __user *filename)

/* This function tries to get a single name component,

 * to send to the server. No actual path traversal involved,

 * so we limit to NAME_MAX */

static char *ll_getname(const char __user *filename)

{

	int ret = 0, len;

	char *tmp = __getname();

	char *tmp;



	tmp = kzalloc(NAME_MAX + 1, GFP_KERNEL);

	if (!tmp)

		return ERR_PTR(-ENOMEM);



	len = strncpy_from_user(tmp, filename, PATH_MAX);

	if (len == 0)

	len = strncpy_from_user(tmp, filename, NAME_MAX + 1);

	if (len < 0)

		ret = len;

	else if (len == 0)

		ret = -ENOENT;

	else if (len > PATH_MAX)

	else if (len > NAME_MAX && tmp[NAME_MAX] != 0)

		ret = -ENAMETOOLONG;



	if (ret) {

		__putname(tmp);

		kfree(tmp);

		tmp =  ERR_PTR(ret);

	}

	return tmp;

}



#define ll_putname(filename) __putname(filename)

#define ll_putname(filename) kfree(filename)



static long ll_dir_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{