[PATCH net] strparser: Do not call mod_delayed_work with a timeout of LONG_MAX

[PATCH net] strparser: Do not call mod_delayed_work with a timeout of LONG_MAX

[Doron Roberts-Kedes]

struct sock's sk_rcvtimeo is initialized to
LONG_MAX/MAX_SCHEDULE_TIMEOUT in sock_init_data. Calling
mod_delayed_work with a timeout of LONG_MAX causes spurious execution of
the work function. timer->expires is set equal to jiffies + LONG_MAX.
When timer_base->clk falls behind the current value of jiffies,
the delta between timer_base->clk and jiffies + LONG_MAX causes the
expiration to be in the past. Returning early from strp_start_timer if
timeo == LONG_MAX solves this problem.

Found while testing net/tls_sw recv path.

Fixes: 43a0c6751a322847 ("strparser: Stream parser for messages")
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
---
 net/strparser/strparser.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
index 805b139..092bebc 100644
--- a/net/strparser/strparser.c
+++ b/net/strparser/strparser.c
@@ -67,7 +67,7 @@ static void strp_abort_strp(struct strparser *strp, int err)
 
 static void strp_start_timer(struct strparser *strp, long timeo)
 {
-	if (timeo)
+	if (timeo && timeo != LONG_MAX)
 		mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);
 }
 
-- 
2.9.5

Re: [PATCH net] strparser: Do not call mod_delayed_work with a timeout of LONG_MAX

[David Miller]

From: Doron Roberts-Kedes <doronrk@fb.com>
Date: Fri, 20 Apr 2018 12:11:11 -0700

> struct sock's sk_rcvtimeo is initialized to
> LONG_MAX/MAX_SCHEDULE_TIMEOUT in sock_init_data. Calling
> mod_delayed_work with a timeout of LONG_MAX causes spurious execution of
> the work function. timer->expires is set equal to jiffies + LONG_MAX.
> When timer_base->clk falls behind the current value of jiffies,
> the delta between timer_base->clk and jiffies + LONG_MAX causes the
> expiration to be in the past. Returning early from strp_start_timer if
> timeo == LONG_MAX solves this problem.
> 
> Found while testing net/tls_sw recv path.
> 
> Fixes: 43a0c6751a322847 ("strparser: Stream parser for messages")
> Reviewed-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>

Applied and queued up for -stable, thanks.