time: jiffies_delta_to_clock_t() helper to the rescue

Various /proc/net files sometimes report crazy timer values, expressed
in clock_t units.

This happens when an expired timer delta (expires - jiffies) is passed
to jiffies_to_clock_t().

This function has an overflow in :

return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);

commit cbbc719fccdb8cb (time: Change jiffies_to_clock_t() argument type
to unsigned long) only got around the problem.

As we cant output negative values in /proc/net/tcp without breaking
various tools, I suggest adding a jiffies_delta_to_clock_t() wrapper
that caps the negative delta to a 0 value.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Maciej Żenczykowski <maze@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: hank <pyu@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 10 insertions, 10 deletions

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 6699f23e6f55..0b5580c69f2d 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -2435,6 +2435,8 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v)
                 struct ip_mc_list *im = (struct ip_mc_list *)v;
                 struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);
                 char   *querier;
+                long delta;
+
 #ifdef CONFIG_IP_MULTICAST
                 querier = IGMP_V1_SEEN(state->in_dev) ? "V1" :
                           IGMP_V2_SEEN(state->in_dev) ? "V2" :
@@ -2448,11 +2450,12 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v)
                                    state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);
                 }
 
+                delta = im->timer.expires - jiffies;
                 seq_printf(seq,
                            "\t\t\t\t%08X %5d %d:%08lX\t\t%d\n",
                            im->multiaddr, im->users,
-                           im->tm_running, im->tm_running ?
-                           jiffies_to_clock_t(im->timer.expires-jiffies) : 0,
+                           im->tm_running,
+                           im->tm_running ? jiffies_delta_to_clock_t(delta) : 0,
                            im->reporter);
         }
         return 0;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 42b2a6a73092..c660d2c19a2b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2385,7 +2385,7 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
                          struct seq_file *f, int i, int uid, int *len)
 {
         const struct inet_request_sock *ireq = inet_rsk(req);
-        int ttd = req->expires - jiffies;
+        long delta = req->expires - jiffies;
 
         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %pK%n",
@@ -2397,7 +2397,7 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
                 TCP_SYN_RECV,
                 0, 0, /* could print option size, but that is af dependent. */
                 1,    /* timers active (only the expire timer) */
-                jiffies_to_clock_t(ttd),
+                jiffies_delta_to_clock_t(delta),
                 req->retrans,
                 uid,
                 0,  /* non standard timer */
@@ -2448,7 +2448,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
                 tp->write_seq - tp->snd_una,
                 rx_queue,
                 timer_active,
-                jiffies_to_clock_t(timer_expires - jiffies),
+                jiffies_delta_to_clock_t(timer_expires - jiffies),
                 icsk->icsk_retransmits,
                 sock_i_uid(sk),
                 icsk->icsk_probes_out,
@@ -2467,10 +2467,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 {
         __be32 dest, src;
         __u16 destp, srcp;
-        int ttd = tw->tw_ttd - jiffies;
-
-        if (ttd < 0)
-                ttd = 0;
+        long delta = tw->tw_ttd - jiffies;
 
         dest  = tw->tw_daddr;
         src   = tw->tw_rcv_saddr;
@@ -2480,7 +2477,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
                 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
-                3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
+                3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
                 atomic_read(&tw->tw_refcnt), tw, len);
 }