Commit caccf691 authored by Quentin Casasnovas's avatar Quentin Casasnovas Committed by Luis Henriques

x86/microcode/intel: Guard against stack overflow in the loader

commit f84598bd upstream.

mc_saved_tmp is a static array allocated on the stack, we need to make
sure mc_saved_count stays within its bounds, otherwise we're overflowing
the stack in _save_mc(). A specially crafted microcode header could lead
to a kernel crash or potentially kernel execution.
Signed-off-by: default avatarQuentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1422964824-22056-1-git-send-email-quentin.casasnovas@oracle.comSigned-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 1d9c16e6
...@@ -321,7 +321,7 @@ get_matching_model_microcode(int cpu, unsigned long start, ...@@ -321,7 +321,7 @@ get_matching_model_microcode(int cpu, unsigned long start,
unsigned int mc_saved_count = mc_saved_data->mc_saved_count; unsigned int mc_saved_count = mc_saved_data->mc_saved_count;
int i; int i;
while (leftover) { while (leftover && mc_saved_count < ARRAY_SIZE(mc_saved_tmp)) {
mc_header = (struct microcode_header_intel *)ucode_ptr; mc_header = (struct microcode_header_intel *)ucode_ptr;
mc_size = get_totalsize(mc_header); mc_size = get_totalsize(mc_header);
......
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