linux-kernel - [ 018/187] bql: Avoid possible inconsistent calculation.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20120712191523.944857458@linuxfoundation.org>
Date:	Thu, 12 Jul 2012 15:32:54 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Hiroaki SHIMODA <shimoda.hiroaki@...il.com>,
	Tom Herbert <therbert@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Denys Fedoryshchenko <denys@...p.net.lb>,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 018/187] bql: Avoid possible inconsistent calculation.

From: Greg KH <gregkh@...uxfoundation.org>

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Hiroaki SHIMODA <shimoda.hiroaki@...il.com>

[ Upstream commit 914bec1011a25f65cdc94988a6f974bfb9a3c10d ]

dql->num_queued could change while processing dql_completed().
To provide consistent calculation, added an on stack variable.

Signed-off-by: Hiroaki SHIMODA <shimoda.hiroaki@...il.com>
Cc: Tom Herbert <therbert@...gle.com>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: Denys Fedoryshchenko <denys@...p.net.lb>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 lib/dynamic_queue_limits.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/lib/dynamic_queue_limits.c
+++ b/lib/dynamic_queue_limits.c
@@ -17,16 +17,18 @@
 void dql_completed(struct dql *dql, unsigned int count)
 {
 	unsigned int inprogress, prev_inprogress, limit;
-	unsigned int ovlimit, completed;
+	unsigned int ovlimit, completed, num_queued;
 	bool all_prev_completed;
 
+	num_queued = ACCESS_ONCE(dql->num_queued);
+
 	/* Can't complete more than what's in queue */
-	BUG_ON(count > dql->num_queued - dql->num_completed);
+	BUG_ON(count > num_queued - dql->num_completed);
 
 	completed = dql->num_completed + count;
 	limit = dql->limit;
-	ovlimit = POSDIFF(dql->num_queued - dql->num_completed, limit);
-	inprogress = dql->num_queued - completed;
+	ovlimit = POSDIFF(num_queued - dql->num_completed, limit);
+	inprogress = num_queued - completed;
 	prev_inprogress = dql->prev_num_queued - dql->num_completed;
 	all_prev_completed = AFTER_EQ(completed, dql->prev_num_queued);
 
@@ -106,7 +108,7 @@ void dql_completed(struct dql *dql, unsi
 	dql->prev_ovlimit = ovlimit;
 	dql->prev_last_obj_cnt = dql->last_obj_cnt;
 	dql->num_completed = completed;
-	dql->prev_num_queued = dql->num_queued;
+	dql->prev_num_queued = num_queued;
 }
 EXPORT_SYMBOL(dql_completed);
 


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/