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ratelimit: Fix data-races in ___ratelimit().

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While reading rs->interval and rs->burst, they can be changed
concurrently via sysctl (e.g. net_ratelimit_state).  Thus, we
need to add READ_ONCE() to their readers.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima 2022-08-23 10:46:48 -07:00 committed by David S. Miller
parent 61adf447e3
commit 6bae8ceb90
1 changed files with 9 additions and 3 deletions
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12
lib/ratelimit.c
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@ -26,10 +26,16 @@
*/ */
int ___ratelimit(struct ratelimit_state *rs, const char *func) int ___ratelimit(struct ratelimit_state *rs, const char *func)
{ {
/* Paired with WRITE_ONCE() in .proc_handler().
* Changing two values seperately could be inconsistent
* and some message could be lost. (See: net_ratelimit_state).
*/
int interval = READ_ONCE(rs->interval);
int burst = READ_ONCE(rs->burst);
unsigned long flags; unsigned long flags;
int ret; int ret;
if (!rs->interval) if (!interval)
return 1; return 1;
/* /*
@ -44,7 +50,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
if (!rs->begin) if (!rs->begin)
rs->begin = jiffies; rs->begin = jiffies;
if (time_is_before_jiffies(rs->begin + rs->interval)) { if (time_is_before_jiffies(rs->begin + interval)) {
if (rs->missed) { if (rs->missed) {
if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) { if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
printk_deferred(KERN_WARNING printk_deferred(KERN_WARNING
@ -56,7 +62,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
rs->begin = jiffies; rs->begin = jiffies;
rs->printed = 0; rs->printed = 0;
} }
if (rs->burst && rs->burst > rs->printed) { if (burst && burst > rs->printed) {
rs->printed++; rs->printed++;
ret = 1; ret = 1;
} else { } else {