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Commit 15279df6 authored by Jann Horn's avatar Jann Horn Committed by Thomas Gleixner
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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: 7f8ec5a4 ("x86/mtrr: Convert to use strncpy_from_user() helper")
Signed-off-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarThomas 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
parent 1268ed0c

arch/x86/kernel/cpu/mtrr/if.c

+2 −1
Original line number Diff line number Diff line
@@ -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;