htb: fix sign extension bug

[ Upstream commit cbd375567f7e4811b1c721f75ec519828ac6583f ]

When userspace passes a large priority value
the assignment of the unsigned value hopt->prio
to  signed int cl->prio causes cl->prio to become negative and the
comparison is with TC_HTB_NUMPRIO is always false.

The result is that HTB crashes by referencing outside
the array when processing packets. With this patch the large value
wraps around like other values outside the normal range.

See: https://bugzilla.kernel.org/show_bug.cgi?id=60669

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 2f074d66377fab2e1850581595d1c338ff335409..9ce5963bbab3b73b3fd5f3d2b3e83544e64113b2 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -85,7 +85,7 @@ struct htb_class {
        unsigned int children;
        struct htb_class *parent;       /* parent class */
 
-       int prio;               /* these two are used only by leaves... */
+       u32 prio;               /* these two are used only by leaves... */
        int quantum;            /* but stored for parent-to-leaf return */
 
        union {