linux_mtd: check ioctl() return value properly

Make the linux_mtd driver treat any negative return value from the
MEMERASE ioctl as an error. Previously it only treated -1 as an error.

BUG=b:213561594,b:210973586,b:182223106
BRANCH=none
TEST=builds

Change-Id: I40cfbdee2ab608fbe6c17d9cac6ec53ff224d9a4
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/60996
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/67857
Reviewed-by: Felix Singer <felixsinger@posteo.net>
---
M linux_mtd.c
1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/linux_mtd.c b/linux_mtd.c
index 75dce1f..7052e5d 100644
--- a/linux_mtd.c
+++ b/linux_mtd.c
@@ -280,9 +280,11 @@
 			.length = mtd_erasesize,
 		};
 
-		if (ioctl(fileno(dev_fp), MEMERASE, &erase_info) == -1) {
-			msg_perr("%s: ioctl: %s\n", __func__, strerror(errno));
-			return 1;
+		int ret = ioctl(fileno(dev_fp), MEMERASE, &erase_info);
+		if (ret < 0) {
+		        msg_perr("%s: MEMERASE ioctl call returned %d, error: %s\n",
+		                 __func__, ret, strerror(errno));
+		        return 1;
 		}
 	}
 

