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Message-Id: <20220329161213.93576-1-dossche.niels@gmail.com> Date: Tue, 29 Mar 2022 18:12:14 +0200 From: Niels Dossche <dossche.niels@...il.com> To: tipc-discussion@...ts.sourceforge.net Cc: netdev@...r.kernel.org, Jon Maloy <jmaloy@...hat.com>, Ying Xue <ying.xue@...driver.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Hoang Le <hoang.h.le@...tech.com.au>, Niels Dossche <dossche.niels@...il.com> Subject: [PATCH net] tipc: use a write lock for keepalive_intv instead of a read lock Currently, n->keepalive_intv is written to while n is locked by a read lock instead of a write lock. This seems to me to break the atomicity against other readers. Change this to a write lock instead to solve the issue. Note: I am currently working on a static analyser to detect missing locks using type-based static analysis as my master's thesis in order to obtain my master's degree. If you would like to have more details, please let me know. This was a reported case. I manually verified the report by looking at the code, so that I do not send wrong information or patches. After concluding that this seems to be a true positive, I created this patch. I have both compile-tested this patch and runtime-tested this patch on x86_64. The effect on a running system could be a potential race condition in exceptional cases. This issue was found on Linux v5.17. Fixes: f5d6c3e5a359 ("tipc: fix node keep alive interval calculation") Signed-off-by: Niels Dossche <dossche.niels@...il.com> --- net/tipc/node.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/tipc/node.c b/net/tipc/node.c index 6ef95ce565bd..da867ddb93f5 100644 --- a/net/tipc/node.c +++ b/net/tipc/node.c @@ -806,9 +806,9 @@ static void tipc_node_timeout(struct timer_list *t) /* Initial node interval to value larger (10 seconds), then it will be * recalculated with link lowest tolerance */ - tipc_node_read_lock(n); + tipc_node_write_lock(n); n->keepalive_intv = 10000; - tipc_node_read_unlock(n); + tipc_node_write_unlock(n); for (bearer_id = 0; remains && (bearer_id < MAX_BEARERS); bearer_id++) { tipc_node_read_lock(n); le = &n->links[bearer_id]; -- 2.35.1
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