[linux-next:master 7646/8170] arch/powerpc/kexec/crash.c:488:2-8: WARNING: NULL check before some freeing functions is not needed.

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   5e4f84f18c4ee9b0ccdc19e39b7de41df21699dd
commit: 849599b702ef8977fcd5b2f27c61ef773c42bb88 [7646/8170] powerpc/crash: add crash memory hotplug support
config: powerpc-randconfig-r061-20240426 (https://download.01.org/0day-ci/archive/20240426/202404261048.skfV5DDB-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 13.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404261048.skfV5DDB-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> arch/powerpc/kexec/crash.c:488:2-8: WARNING: NULL check before some freeing functions is not needed.

vim +488 arch/powerpc/kexec/crash.c

   418	
   419	/**
   420	 * update_crash_elfcorehdr() - Recreate the elfcorehdr and replace it with old
   421	 *			       elfcorehdr in the kexec segment array.
   422	 * @image: the active struct kimage
   423	 * @mn: struct memory_notify data handler
   424	 */
   425	static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *mn)
   426	{
   427		int ret;
   428		struct crash_mem *cmem = NULL;
   429		struct kexec_segment *ksegment;
   430		void *ptr, *mem, *elfbuf = NULL;
   431		unsigned long elfsz, memsz, base_addr, size;
   432	
   433		ksegment = &image->segment[image->elfcorehdr_index];
   434		mem = (void *) ksegment->mem;
   435		memsz = ksegment->memsz;
   436	
   437		ret = get_crash_memory_ranges(&cmem);
   438		if (ret) {
   439			pr_err("Failed to get crash mem range\n");
   440			return;
   441		}
   442	
   443		/*
   444		 * The hot unplugged memory is part of crash memory ranges,
   445		 * remove it here.
   446		 */
   447		if (image->hp_action == KEXEC_CRASH_HP_REMOVE_MEMORY) {
   448			base_addr = PFN_PHYS(mn->start_pfn);
   449			size = mn->nr_pages * PAGE_SIZE;
   450			ret = remove_mem_range(&cmem, base_addr, size);
   451			if (ret) {
   452				pr_err("Failed to remove hot-unplugged memory from crash memory ranges\n");
   453				goto out;
   454			}
   455		}
   456	
   457		ret = crash_prepare_elf64_headers(cmem, false, &elfbuf, &elfsz);
   458		if (ret) {
   459			pr_err("Failed to prepare elf header\n");
   460			goto out;
   461		}
   462	
   463		/*
   464		 * It is unlikely that kernel hit this because elfcorehdr kexec
   465		 * segment (memsz) is built with addition space to accommodate growing
   466		 * number of crash memory ranges while loading the kdump kernel. It is
   467		 * Just to avoid any unforeseen case.
   468		 */
   469		if (elfsz > memsz) {
   470			pr_err("Updated crash elfcorehdr elfsz %lu > memsz %lu", elfsz, memsz);
   471			goto out;
   472		}
   473	
   474		ptr = __va(mem);
   475		if (ptr) {
   476			/* Temporarily invalidate the crash image while it is replaced */
   477			xchg(&kexec_crash_image, NULL);
   478	
   479			/* Replace the old elfcorehdr with newly prepared elfcorehdr */
   480			memcpy((void *)ptr, elfbuf, elfsz);
   481	
   482			/* The crash image is now valid once again */
   483			xchg(&kexec_crash_image, image);
   484		}
   485	out:
   486		kvfree(cmem);
   487		if (elfbuf)
 > 488			kvfree(elfbuf);
   489	}
   490	

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