From: Yicong Yang <yangyicong@hisilicon.com>
To: <viro@zeniv.linux.org.uk>, <akpm@linux-foundation.org>,
<linux-fsdevel@vger.kernel.org>
Cc: <akinobu.mita@gmail.com>, <linux-kernel@vger.kernel.org>,
<linuxarm@huawei.com>, <prime.zeng@huawei.com>,
<yangyicong@hisilicon.com>
Subject: [PATCH v2] libfs: fix error cast of negative value in simple_attr_write()
Date: Fri, 13 Nov 2020 17:56:09 +0800 [thread overview]
Message-ID: <1605261369-551-1-git-send-email-yangyicong@hisilicon.com> (raw)
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.
Fixes: f7b88631a897 ("fs/libfs.c: fix simple_attr_write() on 32bit machines")
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
Change since v1:
- address the compile warning for non-64 bit platform
fs/libfs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/libfs.c b/fs/libfs.c
index fc34361..3a0d99c 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -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, (unsigned long long *)&val);
+ if (ret)
+ goto out;
ret = attr->set(attr->data, val);
if (ret == 0)
ret = len; /* on success, claim we got the whole input */
--
2.8.1
next reply other threads:[~2020-11-13 9:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 9:56 Yicong Yang [this message]
2020-11-13 11:27 ` [PATCH v2] libfs: fix error cast of negative value in simple_attr_write() David Laight
2020-11-13 12:35 ` Al Viro
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