[Drbd-dev] [PATCH] block/drbd: Fix a sleep-in-atomic bug in notify_helper

Jia-Ju Bai baijiaju1990 at 163.com
Wed Oct 4 03:37:29 CEST 2017

The driver may sleep under a RCU lock, and the function call path is:
drbd_sync_handshake (acquire the RCU lock)
        genlmsg_new(GFP_NOIO) --> may sleep

To fix it, GFP_NOIO is replaced with GFP_ATOMIC.
This bug is found by my static analysis tool and my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990 at 163.com>
 drivers/block/drbd/drbd_nl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index a12f77e..ad093da 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -4790,7 +4790,7 @@ void notify_helper(enum drbd_notification_type type,
 	helper_info.helper_name_len = min(strlen(name), sizeof(helper_info.helper_name));
 	helper_info.helper_status = status;
-	skb = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+	skb = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
 	err = -ENOMEM;
 	if (!skb)
 		goto fail;

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