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Commit 8dd5f584 authored by Yicong Yang's avatar Yicong Yang Committed by Greg Kroah-Hartman
Browse files

libfs: fix error cast of negative value in simple_attr_write() 



[ Upstream commit 488dac0c9237647e9b8f788b6a342595bfa40bda ]

The attr->set() receive a value of u64, but simple_strtoll() is used for
doing the conversion.  It will lead to the error cast if user inputs a
negative value.

Use kstrtoull() instead of simple_strtoll() to convert a string got from
the user to an unsigned value.  The former will return '-EINVAL' if it
gets a negetive value, but the latter can't handle the situation
correctly.  Make 'val' unsigned long long as what kstrtoull() takes,
this will eliminate the compile warning on no 64-bit architectures.

Fixes: f7b88631 ("fs/libfs.c: fix simple_attr_write() on 32bit machines")
Signed-off-by: default avatarYicong Yang <yangyicong@hisilicon.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lkml.kernel.org/r/1605341356-11872-1-git-send-email-yangyicong@hisilicon.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent dacd38a5

fs/libfs.c

+4 −2
Original line number Diff line number Diff line
@@ -865,7 +865,7 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf, 
			  size_t len, loff_t *ppos)

{

	struct simple_attr *attr;

	u64 val;

	unsigned long long val;

	size_t size;

	ssize_t ret;
@@ -883,7 +883,9 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf, 
		goto out;



	attr->set_buf[size] = '\0';

	val = simple_strtoll(attr->set_buf, NULL, 0);

	ret = kstrtoull(attr->set_buf, 0, &val);

	if (ret)

		goto out;

	ret = attr->set(attr->data, val);

	if (ret == 0)

		ret = len; /* on success, claim we got the whole input */