[flashrom-gerrit] Change in flashrom[master]: dummyflasher.c: Prevent use-after-free bug

[Angel Pons (Code Review)]

Angel Pons has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/54909 )

Change subject: dummyflasher.c: Prevent use-after-free bug
......................................................................

dummyflasher.c: Prevent use-after-free bug

The memory for the `status` string is aliased by the `endptr` pointer.
Moreover, `errno` could have been modified by the call to `free()`.
Therefore, only free the former when there are no more uses of either.

Change-Id: I1b56834004fe18918213a7df0a09a8a7ecb56985
Signed-off-by: Angel Pons 
---
M dummyflasher.c
1 file changed, 2 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/09/54909/1

diff --git a/dummyflasher.c b/dummyflasher.c
index 78f3837..5109483 100644
--- a/dummyflasher.c
+++ b/dummyflasher.c
@@ -973,12 +973,13 @@
    	char *endptr;
    	errno = 0;
    	data->emu_status = strtoul(status, &endptr, 0);
-		free(status);
    	if (errno != 0 || status == endptr) {
+			free(status);
    		msg_perr("Error: initial status register specified, "
    			 "but the value could not be converted.\n");
    		return 1;
    	}
+		free(status);
    	msg_pdbg("Initial status register is set to 0x%02x.\n",
    		 data->emu_status);
    }