| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 073/144] x86/microcode/intel: Guard against stack overflow in the loader | Date | Tue, 21 Apr 2015 16:30:58 +0100 |
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3.16.7-ckt10 -stable review patch. If anyone has any objections, please let me know.
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From: Quentin Casasnovas <quentin.casasnovas@oracle.com>
commit f84598bd7c851f8b0bf8cd0d7c3be0d73c432ff4 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: 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> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/x86/kernel/cpu/microcode/intel_early.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c index 18f739129e72..43a07bf48dea 100644 --- a/arch/x86/kernel/cpu/microcode/intel_early.c +++ b/arch/x86/kernel/cpu/microcode/intel_early.c @@ -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);
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