linux-kernel - [PATCH v2 02/11] block: sed-opal: unify space check in add_token

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Message-Id: <955fd10854ed68f6925612ae73cdaa4637cfb5e4.1521482295.git.jonas.rabenstein@studium.uni-erlangen.de>
Date:   Mon, 19 Mar 2018 19:36:44 +0100
From:   Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
To:     Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>,
        Scott Bauer <scott.bauer@...el.com>,
        Jonathan Derrick <jonathan.derrick@...el.com>,
        Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v2 02/11] block: sed-opal: unify space check in add_token_*

All add_token_* functions have a common set of conditions that have to
be checked. Use a common function for those checks in order to avoid
different behaviour as well as code duplication.

Signed-off-by: Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>

diff --git a/block/sed-opal.c b/block/sed-opal.c
index 5aa41744b8f1..771b4cfff95c 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c
@@ -510,15 +510,24 @@ static int opal_discovery0(struct opal_dev *dev, void *data)
 	return opal_discovery0_end(dev);
 }
 
-static void add_token_u8(int *err, struct opal_dev *cmd, u8 tok)
+static bool can_add(int *err, struct opal_dev *cmd, size_t len)
 {
 	if (*err)
-		return;
-	if (cmd->pos >= IO_BUFFER_LENGTH - 1) {
-		pr_debug("Error adding u8: end of buffer.\n");
+		return false;
+
+	if (len > IO_BUFFER_LENGTH || cmd->pos >= IO_BUFFER_LENGTH - len) {
+		pr_debug("Error adding %zu bytes: end of buffer.\n", len);
 		*err = -ERANGE;
-		return;
+		return false;
 	}
+
+	return true;
+}
+
+static void add_token_u8(int *err, struct opal_dev *cmd, u8 tok)
+{
+	if (!can_add(err, cmd, 1))
+		return;
 	cmd->cmd[cmd->pos++] = tok;
 }
 
@@ -563,9 +572,8 @@ static void add_token_u64(int *err, struct opal_dev *cmd, u64 number)
 	msb = fls64(number);
 	len = DIV_ROUND_UP(msb, 8);
 
-	if (cmd->pos >= IO_BUFFER_LENGTH - len - 1) {
+	if (!can_add(err, cmd, len + 1)) {
 		pr_debug("Error adding u64: end of buffer.\n");
-		*err = -ERANGE;
 		return;
 	}
 	add_short_atom_header(cmd, false, false, len);
@@ -587,9 +595,8 @@ static void add_token_bytestring(int *err, struct opal_dev *cmd,
 		is_short_atom = false;
 	}
 
-	if (len >= IO_BUFFER_LENGTH - cmd->pos - header_len) {
+	if (!can_add(err, cmd, header_len + len)) {
 		pr_debug("Error adding bytestring: end of buffer.\n");
-		*err = -ERANGE;
 		return;
 	}
 
-- 
2.16.1