[PATCH] dm-inlinecrypt: Fix signedness bug

[Ethan Tidmore <ethantidmore06@gmail.com>]

The function get_key_size() returns negative error codes and
ctx->key_size is an unsigned integer, so the check (ctx->key_size < 0)
is always impossible

Assign get_key_size() return value to err, check for error code, then
assign ctx->key_size to err.

Detected by Smatch:
drivers/md/dm-inlinecrypt.c:329 inlinecrypt_ctr()
warn: unsigned 'ctx->key_size' is never less than zero.

Fixes: 753450f716417 ("dm-inlinecrypt: add target for inline block device encryption")
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
---
 drivers/md/dm-inlinecrypt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-inlinecrypt.c b/drivers/md/dm-inlinecrypt.c
index 6f804f5a4be6..40d48ba73e23 100644
--- a/drivers/md/dm-inlinecrypt.c
+++ b/drivers/md/dm-inlinecrypt.c
@@ -325,11 +325,13 @@ static int inlinecrypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	}
 
 	/* <key> */
-	ctx->key_size = get_key_size(&argv[1]);
-	if (ctx->key_size < 0) {
+	err = get_key_size(&argv[1]);
+	if (err < 0) {
 		ti->error = "Cannot parse key size";
 		return -EINVAL;
 	}
+	ctx->key_size = err;
+
 	err = inlinecrypt_get_key(argv[1], raw_key, ctx->key_size);
 	if (err) {
 		ti->error = "Malformed key string";
-- 
2.54.0