From: Yicong Yang yangyicong@hisilicon.com
[ 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: f7b88631a897 ("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@hisil... Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/libfs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c index e0d42e977d9af..7bf691979a584 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -957,7 +957,7 @@ 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;
@@ -975,7 +975,9 @@ 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 */