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>

1 files changed, 22 insertions, 16 deletions

diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c
index d515ff3feb8b..95516006958d 100644
--- 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;
 }