linux-kernel - [PATCH] x86/microcode/amd: fix uninitalized structure cp

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Date:   Tue, 14 Jan 2020 11:15:05 +0000
From:   Colin King <colin.king@...onical.com>
To:     Borislav Petkov <bp@...e.de>, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] x86/microcode/amd: fix uninitalized structure cp

From: Colin Ian King <colin.king@...onical.com>

In the case where cp is not assigned to the return from
the call to find_microcode_in_initrd cp is uninitialized when
it is assigned to *ret.   Functions that call __load_ucode_amd
such as load_ucode_amd_bsp can therefore end up checking bogus
values cp.data and cp.size.  Fix this by ensuring cp is
initialized as all zero and remove the redundant initialization
of cp in load_ucode_amd_bsp.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: e71bb4ec0739 ("x86/microcode/AMD: Unify load_ucode_amd_ap()")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 arch/x86/kernel/cpu/microcode/amd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 3f6b137ef4e6..675704019df2 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -473,7 +473,7 @@ static bool get_builtin_microcode(struct cpio_data *cp, unsigned int family)
 static void __load_ucode_amd(unsigned int cpuid_1_eax, struct cpio_data *ret)
 {
 	struct ucode_cpu_info *uci;
-	struct cpio_data cp;
+	struct cpio_data cp = { };
 	const char *path;
 	bool use_pa;
 
@@ -498,7 +498,7 @@ static void __load_ucode_amd(unsigned int cpuid_1_eax, struct cpio_data *ret)
 
 void __init load_ucode_amd_bsp(unsigned int cpuid_1_eax)
 {
-	struct cpio_data cp = { };
+	struct cpio_data cp;
 
 	__load_ucode_amd(cpuid_1_eax, &cp);
 	if (!(cp.data && cp.size))
-- 
2.24.0