lkml.org 
[lkml]   [2018]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip:x86/urgent] x86/mtrr: Don't copy out-of-bounds data in mtrr_write
    Commit-ID:  15279df6f26cf2013d713904b4a0c957ae8abb96
    Gitweb: https://git.kernel.org/tip/15279df6f26cf2013d713904b4a0c957ae8abb96
    Author: Jann Horn <jannh@google.com>
    AuthorDate: Fri, 6 Jul 2018 23:50:03 +0200
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Sat, 7 Jul 2018 18:58:41 +0200

    x86/mtrr: Don't copy out-of-bounds data in mtrr_write

    Don't access the provided buffer out of bounds - this can cause a kernel
    out-of-bounds read when invoked through sys_splice() or other things that
    use kernel_write()/__kernel_write().

    Fixes: 7f8ec5a4f01a ("x86/mtrr: Convert to use strncpy_from_user() helper")
    Signed-off-by: Jann Horn <jannh@google.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: stable@vger.kernel.org
    Link: https://lkml.kernel.org/r/20180706215003.156702-1-jannh@google.com

    ---
    arch/x86/kernel/cpu/mtrr/if.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c
    index 4021d3859499..40eee6cc4124 100644
    --- a/arch/x86/kernel/cpu/mtrr/if.c
    +++ b/arch/x86/kernel/cpu/mtrr/if.c
    @@ -106,7 +106,8 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)

    memset(line, 0, LINE_SIZE);

    - length = strncpy_from_user(line, buf, LINE_SIZE - 1);
    + len = min_t(size_t, len, LINE_SIZE - 1);
    + length = strncpy_from_user(line, buf, len);
    if (length < 0)
    return length;

    \
     
     \ /
      Last update: 2018-07-07 19:05    [W:4.962 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site