powerpc: Free fdt on error in elf64_load()

There are a few "goto out;" statements before the local variable "fdt"
is initialized through the call to of_kexec_alloc_and_setup_fdt() in
elf64_load().  This will result in an uninitialized "fdt" being passed
to kvfree() in this function if there is an error before the call to
of_kexec_alloc_and_setup_fdt().

If there is any error after fdt is allocated, but before it is
saved in the arch specific kimage struct, free the fdt.

Fixes: 3c985d31 ("powerpc: Use common of_kexec_alloc_and_setup_fdt()")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210421163610.23775-1-nramas@linux.microsoft.com

arch/powerpc/kexec/elf_64.c

@@ -114,7 +114,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	ret = setup_new_fdt_ppc64(image, fdt, initrd_load_addr,
 				  initrd_len, cmdline);
 	if (ret)
-		goto out;
+		goto out_free_fdt;
 
 	fdt_pack(fdt);
 
@@ -125,7 +125,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 	ret = kexec_add_buffer(&kbuf);
 	if (ret)
-		goto out;
+		goto out_free_fdt;
 
 	/* FDT will be freed in arch_kimage_file_post_load_cleanup */
 	image->arch.fdt = fdt;
@@ -140,18 +140,14 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	if (ret)
 		pr_err("Error setting up the purgatory.\n");
 
+	goto out;
+
+out_free_fdt:
+	kvfree(fdt);
 out:
 	kfree(modified_cmdline);
 	kexec_free_elf_info(&elf_info);
 
-	/*
-	 * Once FDT buffer has been successfully passed to kexec_add_buffer(),
-	 * the FDT buffer address is saved in image->arch.fdt. In that case,
-	 * the memory cannot be freed here in case of any other error.
-	 */
-	if (ret && !image->arch.fdt)
-		kvfree(fdt);
-
 	return ret ? ERR_PTR(ret) : NULL;
 }