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

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: Quentin 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.com
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Quentin Casasnovas 2015-02-03 13:00:22 +01:00 committed by Borislav Petkov
parent e36f014edf
commit f84598bd7c
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/cpu/microcode/intel_early.c
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@ -321,7 +321,7 @@ get_matching_model_microcode(int cpu, unsigned long start,
unsigned int mc_saved_count = mc_saved_data->mc_saved_count;
int i;
while (leftover) {
while (leftover && mc_saved_count < ARRAY_SIZE(mc_saved_tmp)) {
mc_header = (struct microcode_header_intel *)ucode_ptr;
mc_size = get_totalsize(mc_header);