[PATCH 5.13 109/151] net: igmp: increase size of mr_ifc_count

Greg Kroah-Hartman
2021-08-16T13:29:51Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit b69dd5b3780a7298bd893816a09da751bc0636f7 ]

Some arches support cmpxchg() on 4-byte and 8-byte only.
Increase mr_ifc_count width to 32bit to fix this problem.

Fixes: 4a2b285e7e10 ("net: igmp: fix data-race in igmp_ifc_timer_expire()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210811195715.3684218-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/inetdevice.h | 2 +-
net/ipv4/igmp.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 53aa0343bf69..aaf4f1b4c277 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -41,7 +41,7 @@ struct in_device {
unsigned long mr_qri; /* Query Response Interval */
unsigned char mr_qrv; /* Query Robustness Variable */
unsigned char mr_gq_running;
- unsigned char mr_ifc_count;
+ u32 mr_ifc_count;
struct timer_list mr_gq_timer; /* general query timer */
struct timer_list mr_ifc_timer; /* interface change timer */

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index a51360087b19..00576bae183d 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -803,7 +803,7 @@ static void igmp_gq_timer_expire(struct timer_list *t)
static void igmp_ifc_timer_expire(struct timer_list *t)
{
struct in_device *in_dev = from_timer(in_dev, t, mr_ifc_timer);
- u8 mr_ifc_count;
+ u32 mr_ifc_count;

igmpv3_send_cr(in_dev);
restart:
--
2.30.2