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

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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: f7b88631a8 ("fs/libfs.c: fix simple_attr_write() on 32bit machines")
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Andrew 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yicong Yang 2020-11-21 22:17:19 -08:00 committed by Linus Torvalds
parent bfe8cc1db0
commit 488dac0c92
1 changed files with 4 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

6
fs/libfs.c
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@ -959,7 +959,7 @@ 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;
@ -977,7 +977,9 @@ 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 */