This is a note to let you know that I've just added the patch titled
libfs: fix error cast of negative value in simple_attr_write()
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
libfs-fix-error-cast-of-negative-value-in-simple_att.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5b21aa08eaf66be89d99850d76ab47838bc9b533
Author: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Date: Sat Nov 21 22:17:19 2020 -0800
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: f7b88631a897 ("fs/libfs.c: fix simple_attr_write() on 32bit machines")
Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/1605341356-11872-1-git-send-email-yangyicong@xxxxxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 */
