Commit-ID: 15279df6f26cf2013d713904b4a0c957ae8abb96 Gitweb: https://git.kernel.org/tip/15279df6f26cf2013d713904b4a0c957ae8abb96 Author: Jann Horn <ja...@google.com> AuthorDate: Fri, 6 Jul 2018 23:50:03 +0200 Committer: Thomas Gleixner <t...@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 <ja...@google.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: Andy Shevchenko <andriy.shevche...@linux.intel.com> Cc: "H. Peter Anvin" <h...@zytor.com> Cc: sta...@vger.kernel.org Link: https://lkml.kernel.org/r/20180706215003.156702-1-ja...@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;