s390/kdump: Fix memleak in nt_vmcoreinfo

[ Upstream commit 2d2e7075 ]

The vmcoreinfo of a crashed system is potentially fragmented. Thus the
crash kernel has an intermediate step where the vmcoreinfo is copied into a
temporary, continuous buffer in the crash kernel memory. This temporary
buffer is never freed. Free it now to prevent the memleak.

While at it replace all occurrences of "VMCOREINFO" by its corresponding
macro to prevent potential renaming issues.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/s390/kernel/crash_dump.c

@@ -401,11 +401,13 @@ static void *get_vmcoreinfo_old(unsigned long *size)
 	if (copy_oldmem_kernel(nt_name, addr + sizeof(note),
 			       sizeof(nt_name) - 1))
 		return NULL;
-	if (strcmp(nt_name, "VMCOREINFO") != 0)
+	if (strcmp(nt_name, VMCOREINFO_NOTE_NAME) != 0)
 		return NULL;
 	vmcoreinfo = kzalloc_panic(note.n_descsz);
-	if (copy_oldmem_kernel(vmcoreinfo, addr + 24, note.n_descsz))
+	if (copy_oldmem_kernel(vmcoreinfo, addr + 24, note.n_descsz)) {
+		kfree(vmcoreinfo);
 		return NULL;
+	}
 	*size = note.n_descsz;
 	return vmcoreinfo;
 }
@@ -415,15 +417,20 @@ static void *get_vmcoreinfo_old(unsigned long *size)
  */
 static void *nt_vmcoreinfo(void *ptr)
 {
+	const char *name = VMCOREINFO_NOTE_NAME;
 	unsigned long size;
 	void *vmcoreinfo;
 
 	vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
-	if (!vmcoreinfo)
-		vmcoreinfo = get_vmcoreinfo_old(&size);
+	if (vmcoreinfo)
+		return nt_init_name(ptr, 0, vmcoreinfo, size, name);
+
+	vmcoreinfo = get_vmcoreinfo_old(&size);
 	if (!vmcoreinfo)
 		return ptr;
-	return nt_init_name(ptr, 0, vmcoreinfo, size, "VMCOREINFO");
+	ptr = nt_init_name(ptr, 0, vmcoreinfo, size, name);
+	kfree(vmcoreinfo);
+	return ptr;
 }
 
 /*