lkml.org 
[lkml]   [2020]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.9 33/47] libfs: fix error cast of negative value in simple_attr_write()
    Date
    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@hisilicon.com
    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 278457f221482..835d25e335095 100644
    --- a/fs/libfs.c
    +++ b/fs/libfs.c
    @@ -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 */
    --
    2.27.0


    \
     
     \ /
      Last update: 2020-11-23 13:39    [W:4.132 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site