linux-kernel - [PATCH] firmware: fix async/manual firmware loading

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Date:   Sun, 30 Oct 2016 15:50:48 +0100
From:   Yves-Alexis Perez <corsac@...sac.net>
To:     linux-kernel@...r.kernel.org
Cc:     Yves-Alexis Perez <corsac@...ian.org>,
        Yves-Alexis Perez <corsac@...sac.net>,
        Ming Lei <ming.lei@...onical.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org
Subject: [PATCH] firmware: fix async/manual firmware loading

From: Yves-Alexis Perez <corsac@...ian.org>

wait_for_completion_interruptible_timeout() return value is either
-ERESTARTSYS (in case it was interrupted), 0 (in case the timeout expired)
or the number of jiffies left until timeout. The return value is stored in
a long, but in _request_firmware_load() it's silently casted to an int,
which can overflow and give a negative value, indicating an error.

Fix this by re-using the timeout variable and only set retval when it's
safe.

Signed-off-by: Yves-Alexis Perez <corsac@...sac.net>
Cc: Ming Lei <ming.lei@...onical.com>
Cc: "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: stable@...r.kernel.org

---
 drivers/base/firmware_class.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 22d1760..a95e1e5 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -955,13 +955,14 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
 		timeout = MAX_JIFFY_OFFSET;
 	}
 
-	retval = wait_for_completion_interruptible_timeout(&buf->completion,
+	timeout = wait_for_completion_interruptible_timeout(&buf->completion,
 			timeout);
-	if (retval == -ERESTARTSYS || !retval) {
+	if (timeout == -ERESTARTSYS || !timeout) {
+		retval = timeout;
 		mutex_lock(&fw_lock);
 		fw_load_abort(fw_priv);
 		mutex_unlock(&fw_lock);
-	} else if (retval > 0) {
+	} else if (timeout > 0) {
 		retval = 0;
 	}
 
-- 
2.10.1