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ipv6: mcast: use jiffies_delta_to_clock_t() in igmp6_mc_seq_show()

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If a multicast group timer has expired but the delayed work has
not yet run to clear MAF_TIMER_RUNNING, expires - jiffies produces
a negative value.

Because unsigned arithmetic was used with jiffies_to_clock_t(),
expires - jiffies underflows to a huge value and reports invalid
timer durations in /proc/net/igmp6.

Use jiffies_delta_to_clock_t() with a signed long delta to properly
cap expired deltas to 0, matching IPv4 igmp_mc_seq_show() and commit
a399a80531 ("time: jiffies_delta_to_clock_t() helper to the rescue").

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260828084531.1826790-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-08-28 08:45:31 +00:00 committed by Jakub Kicinski
parent 0c8f56c583
commit b4cf4a092a
1 changed files with 2 additions and 2 deletions
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4
net/ipv6/mcast.c
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@ -3029,7 +3029,7 @@ static int igmp6_mc_seq_show(struct seq_file *seq, void *v)
struct ifmcaddr6 *im = (struct ifmcaddr6 *)v;
struct igmp6_mc_iter_state *state = igmp6_mc_seq_private(seq);
unsigned int mca_flags = READ_ONCE(im->mca_flags);
unsigned long expires = READ_ONCE(im->mca_work.timer.expires);
long delta = READ_ONCE(im->mca_work.timer.expires) - jiffies;
seq_printf(seq,
"%-4d %-15s %pi6 %5d %08X %ld\n",
@ -3037,7 +3037,7 @@ static int igmp6_mc_seq_show(struct seq_file *seq, void *v)
&im->mca_addr,
READ_ONCE(im->mca_users), mca_flags,
(mca_flags & MAF_TIMER_RUNNING) ?
jiffies_to_clock_t(expires - jiffies) : 0);
jiffies_delta_to_clock_t(delta) : 0);
return 0;
}