From: Gerd Hoffmann <[email protected]>

Verify the passed buffer has the minimal required length before
reading the size field + verifying the total length.

Fixes: CVE-2026-58581
Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3614
Acked-by: Luigi Leonardi <[email protected]>
Signed-off-by: Gerd Hoffmann <[email protected]>
Message-ID: <[email protected]>
(cherry picked from commit 702216619e2a1afd5039520114f4d245d7011f09)
Signed-off-by: Michael Tokarev <[email protected]>

diff --git a/hw/uefi/var-service-policy.c b/hw/uefi/var-service-policy.c
index 58da4adbeba..989bf87ddb8 100644
--- a/hw/uefi/var-service-policy.c
+++ b/hw/uefi/var-service-policy.c
@@ -276,6 +276,9 @@ static uint32_t 
uefi_vars_mm_check_policy_register(uefi_vars_state *uv,
     uefi_var_policy *pol;
     uint64_t length;
 
+    if (mhdr->length < sizeof(*mchk) + sizeof(*pe)) {
+        return uefi_vars_mm_policy_error(mhdr, mchk, EFI_BAD_BUFFER_SIZE);
+    }
     if (uadd64_overflow(sizeof(*mchk), pe->size, &length)) {
         return uefi_vars_mm_policy_error(mhdr, mchk, EFI_BAD_BUFFER_SIZE);
     }
-- 
2.47.3


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