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Subject[PATCH v1 net 15/16] icmp: Fix data-races around sysctl.
Date
While reading sysctl variables, it can be changed concurrently.  So, we
need to add READ_ONCE(). Then we can set proc_dointvec_minmax_lockless()
as the handler to mark it safe.

Fixes: 4cdf507d5452 ("icmp: add a global rate limitation")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
net/ipv4/icmp.c | 5 +++--
net/ipv4/sysctl_net_ipv4.c | 4 ++--
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index efea0e796f06..0f9e61d29f73 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -253,11 +253,12 @@ bool icmp_global_allow(void)
spin_lock(&icmp_global.lock);
delta = min_t(u32, now - icmp_global.stamp, HZ);
if (delta >= HZ / 50) {
- incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
+ incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
if (incr)
WRITE_ONCE(icmp_global.stamp, now);
}
- credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
+ credit = min_t(u32, icmp_global.credit + incr,
+ READ_ONCE(sysctl_icmp_msgs_burst));
if (credit) {
/* We want to use a credit of one in average, but need to randomize
* it for security reasons.
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 706795a3b369..3b1d18be0857 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -555,7 +555,7 @@ static struct ctl_table ipv4_table[] = {
.data = &sysctl_icmp_msgs_per_sec,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax_lockless,
.extra1 = SYSCTL_ZERO,
},
{
@@ -563,7 +563,7 @@ static struct ctl_table ipv4_table[] = {
.data = &sysctl_icmp_msgs_burst,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax_lockless,
.extra1 = SYSCTL_ZERO,
},
{
--
2.30.2
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