tpm: Do not dereference NULL pointer if acpi_os_map_memory() fails.

In drivers/char/tpm/tpm_acpi.c::read_log() we call acpi_os_map_memory(). That call may fail for a number of reasons (invalid address, out of memory etc). If the call fails it returns NULL and we just pass that to memcpy() unconditionally, which will go bad when it tries to dereference the pointer. Unfortunately we just get NULL back, so we can't really tell the user exactely what went wrong, but we can at least avoid crashing and return an error (-EIO seemed more generic and more suitable here than -ENOMEM or something else, so I picked that). Signed-off-by: Jesper Juhl <[email protected]> Signed-off-by: Kent Yoder <[email protected]>
jimmycarry · Aug 22, 2012 · f334ac8 · f334ac8
1 parent 20328b5
commit f334ac8
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
@@ -96,6 +96,11 @@ int read_log(struct tpm_bios_log *log)
 	log->bios_event_log_end = log->bios_event_log + len;
 
 	virt = acpi_os_map_memory(start, len);
+	if (!virt) {
+		kfree(log->bios_event_log);
+		printk("%s: ERROR - Unable to map memory\n", __func__);
+		return -EIO;
+	}
 
 	memcpy(log->bios_event_log, virt, len);