x86/microcode/intel: Do the mc_saved_src NULL check first

... and only then deref it. Also, shorten some variable names and rename
others so as to diminish the ubiquitous presence of the "mc_" prefix
everywhere and make it a bit more readable.

Use kcalloc so that we don't kfree() uninitialized memory on the unwind
path, as suggested by Quentin.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>

diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c
index d515ff3..9551600 100644 (file)
--- a/arch/x86/kernel/cpu/microcode/intel_early.c
+++ b/arch/x86/kernel/cpu/microcode/intel_early.c
@@ -203,7 +203,7 @@ save_microcode(struct mc_saved_data *mc_saved_data,
               unsigned int mc_saved_count)
 {
        int i, j;
-       struct microcode_intel **mc_saved_p;
+       struct microcode_intel **saved_ptr;
        int ret;
 
        if (!mc_saved_count)
@@ -212,39 +212,45 @@ save_microcode(struct mc_saved_data *mc_saved_data,
        /*
         * Copy new microcode data.
         */
-       mc_saved_p = kmalloc(mc_saved_count*sizeof(struct microcode_intel *),
-                            GFP_KERNEL);
-       if (!mc_saved_p)
+       saved_ptr = kcalloc(mc_saved_count, sizeof(struct microcode_intel *), GFP_KERNEL);
+       if (!saved_ptr)
                return -ENOMEM;
 
        for (i = 0; i < mc_saved_count; i++) {
-               struct microcode_intel *mc = mc_saved_src[i];
-               struct microcode_header_intel *mc_header = &mc->hdr;
-               unsigned long mc_size = get_totalsize(mc_header);
-               mc_saved_p[i] = kmalloc(mc_size, GFP_KERNEL);
-               if (!mc_saved_p[i]) {
-                       ret = -ENOMEM;
-                       goto err;
-               }
+               struct microcode_header_intel *mc_hdr;
+               struct microcode_intel *mc;
+               unsigned long size;
+
                if (!mc_saved_src[i]) {
                        ret = -EINVAL;
                        goto err;
                }
-               memcpy(mc_saved_p[i], mc, mc_size);
+
+               mc     = mc_saved_src[i];
+               mc_hdr = &mc->hdr;
+               size   = get_totalsize(mc_hdr);
+
+               saved_ptr[i] = kmalloc(size, GFP_KERNEL);
+               if (!saved_ptr[i]) {
+                       ret = -ENOMEM;
+                       goto err;
+               }
+
+               memcpy(saved_ptr[i], mc, size);
        }
 
        /*
         * Point to newly saved microcode.
         */
-       mc_saved_data->mc_saved = mc_saved_p;
+       mc_saved_data->mc_saved = saved_ptr;
        mc_saved_data->mc_saved_count = mc_saved_count;
 
        return 0;
 
 err:
        for (j = 0; j <= i; j++)
-               kfree(mc_saved_p[j]);
-       kfree(mc_saved_p);
+               kfree(saved_ptr[j]);
+       kfree(saved_ptr);
 
        return ret;
 }