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    Subject[PATCH 5.4 28/77] ratelimit: Fix data-races in ___ratelimit().
    Date
    From: Kuniyuki Iwashima <kuniyu@amazon.com>

    [ Upstream commit 6bae8ceb90ba76cdba39496db936164fa672b9be ]

    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: 1da177e4c3f4 ("Linux-2.6.12-rc2")
    Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    lib/ratelimit.c | 12 +++++++++---
    1 file changed, 9 insertions(+), 3 deletions(-)

    diff --git a/lib/ratelimit.c b/lib/ratelimit.c
    index e01a93f46f833..ce945c17980b9 100644
    --- a/lib/ratelimit.c
    +++ b/lib/ratelimit.c
    @@ -26,10 +26,16 @@
    */
    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;
    int ret;

    - if (!rs->interval)
    + if (!interval)
    return 1;

    /*
    @@ -44,7 +50,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
    if (!rs->begin)
    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->flags & RATELIMIT_MSG_ON_RELEASE)) {
    printk_deferred(KERN_WARNING
    @@ -56,7 +62,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
    rs->begin = jiffies;
    rs->printed = 0;
    }
    - if (rs->burst && rs->burst > rs->printed) {
    + if (burst && burst > rs->printed) {
    rs->printed++;
    ret = 1;
    } else {
    --
    2.35.1


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