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authorJann Horn <jannh@google.com>2018-07-06 23:50:03 +0200
committerThomas Gleixner <tglx@linutronix.de>2018-07-07 18:58:41 +0200
commit15279df6f26cf2013d713904b4a0c957ae8abb96 (patch)
treeab9a3489acdac58d266366cb4539db6a8ca269e7
parent1268ed0c474a5c8f165ef386f3310521b5e00e27 (diff)
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
-rw-r--r--arch/x86/kernel/cpu/mtrr/if.c3
1 files changed, 2 insertions, 1 deletions
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;