4.9-stable review patch. If anyone has any objections, please let me know.
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From: Colin Ian King colin.king@canonical.com
commit 32043fa065b51e0b1433e48d118821c71b5cd65d upstream.
Currently the copy_to_user of data in the gentry struct is copying uninitiaized data in field _pad from the stack to userspace.
Fix this by explicitly memset'ing gentry to zero, this also will zero any compiler added padding fields that may be in struct (currently there are none).
Detected by CoverityScan, CID#200783 ("Uninitialized scalar variable")
Fixes: b263b31e8ad6 ("x86, mtrr: Use explicit sizing and padding for the 64-bit ioctls") Signed-off-by: Colin Ian King colin.king@canonical.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Tyler Hicks tyhicks@canonical.com Cc: security@kernel.org Link: https://lkml.kernel.org/r/20181218172956.1440-1-colin.king@canonical.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/cpu/mtrr/if.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/x86/kernel/cpu/mtrr/if.c +++ b/arch/x86/kernel/cpu/mtrr/if.c @@ -172,6 +172,8 @@ mtrr_ioctl(struct file *file, unsigned i struct mtrr_gentry gentry; void __user *arg = (void __user *) __arg;
+ memset(&gentry, 0, sizeof(gentry)); + switch (cmd) { case MTRRIOC_ADD_ENTRY: case MTRRIOC_SET_ENTRY: