Commit 0761921f authored by Colin Ian King's avatar Colin Ian King Committed by Greg Kroah-Hartman

x86/mtrr: Don't copy uninitialized gentry fields back to userspace

commit 32043fa0 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: b263b31e ("x86, mtrr: Use explicit sizing and padding for the 64-bit ioctls")
Signed-off-by: default avatarColin Ian King <colin.king@canonical.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarTyler Hicks <tyhicks@canonical.com>
Cc: security@kernel.org
Link: https://lkml.kernel.org/r/20181218172956.1440-1-colin.king@canonical.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ff53cc35
......@@ -173,6 +173,8 @@ mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
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:
......
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