[PATCH] net: sunrpc: xprt.c: fix shift-out-of-bounds in xprt_calc_majortimeo

[Kurt Manucredo]

Fix shift-out-of-bounds in xprt_calc_majortimeo().

UBSAN: shift-out-of-bounds in net/sunrpc/xprt.c:658:14
shift exponent 536871232 is too large for 64-bit type 'long u

Reported-by: syzbot+ba2e91df8f7480941...@syzkaller.appspotmail.com
Signed-off-by: Kurt Manucredo <fuzzybritch...@gmail.com>
---
 net/sunrpc/xprt.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 691ccf8049a4..07128ac3d51d 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -655,7 +655,10 @@ static unsigned long xprt_calc_majortimeo(struct rpc_rqst 
*req)
        unsigned long majortimeo = req->rq_timeout;
 
        if (to->to_exponential)
-               majortimeo <<= to->to_retries;
+               if (to->to_retries >= sizeof(majortimeo) * 8)
+                       majortimeo = to->to_maxval;
+               else
+                       majortimeo <<= to->to_retries;
        else
                majortimeo += to->to_increment * to->to_retries;
        if (majortimeo > to->to_maxval || majortimeo == 0)
-- 
2.30.2