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x86/microcode/intel: Handle truncated microcode images more robustly

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We do not check the input data bounds containing the microcode before
copying a struct microcode_intel_header from it. A specially crafted
microcode could cause the kernel to read invalid memory and lead to a
denial-of-service.

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/1422964824-22056-3-git-send-email-quentin.casasnovas@oracle.com
[ Made error message differ from the next one and flipped comparison. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Quentin Casasnovas 2015-02-03 13:00:24 +01:00 committed by Borislav Petkov
parent f84598bd7c
commit 35a9ff4eec
2 changed files with 9 additions and 0 deletions
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5
arch/x86/kernel/cpu/microcode/intel.c
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@ -196,6 +196,11 @@ static enum ucode_state generic_load_microcode(int cpu, void *data, size_t size,
struct microcode_header_intel mc_header;
unsigned int mc_size;
if (leftover < sizeof(mc_header)) {
pr_err("error! Truncated header in microcode data file\n");
break;
}
if (get_ucode_data(&mc_header, ucode_ptr, sizeof(mc_header)))
break;

4
arch/x86/kernel/cpu/microcode/intel_early.c
View file

@ -322,6 +322,10 @@ get_matching_model_microcode(int cpu, unsigned long start,
int i;
while (leftover && mc_saved_count < ARRAY_SIZE(mc_saved_tmp)) {
if (leftover < sizeof(mc_header))
break;
mc_header = (struct microcode_header_intel *)ucode_ptr;
mc_size = get_totalsize(mc_header);