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Subject[PATCH v4 08/10] x86/microcode/AMD: Check microcode container file size before accessing it
Date
The early loader parse_container() function should check whether the
microcode container file is actually large enough to contain the patch of
an indicated size, just like the late loader does.

Also, the request_microcode_amd() function should check whether the
container file is actually large enough to contain the header magic value.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
---
arch/x86/kernel/cpu/microcode/amd.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 4d2116d08754..dc5ed4971879 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -125,6 +125,9 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
struct microcode_amd *mc;
u32 patch_size;

+ if (size < SECTION_HDR_SIZE)
+ break;
+
hdr = (u32 *)buf;

if (hdr[0] != UCODE_UCODE_TYPE)
@@ -139,6 +142,10 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
buf += SECTION_HDR_SIZE;
size -= SECTION_HDR_SIZE;

+ if (size < sizeof(*mc) ||
+ size < patch_size)
+ break;
+
mc = (struct microcode_amd *)buf;
if (eq_id == mc->hdr.processor_rev_id) {
desc->psize = patch_size;
@@ -794,6 +801,10 @@ static enum ucode_state request_microcode_amd(int cpu, struct device *device,
}

ret = UCODE_ERROR;
+ if (fw->size < sizeof(u32)) {
+ pr_err("microcode container far too short\n");
+ goto fw_release;
+ }
if (*(u32 *)fw->data != UCODE_MAGIC) {
pr_err("invalid magic value (0x%08x)\n", *(u32 *)fw->data);
goto fw_release;
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