6.6-stable review patch. If anyone has any objections, please let me know.
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From: Gui-Dong Han hanguidong02@gmail.com
[ Upstream commit 8ca7eada62fcfabf6ec1dc7468941e791c1d8729 ]
When do_task() exhausts its iteration budget (!ret), it sets the state to TASK_STATE_IDLE to reschedule, without a secondary check on the current task->state. This can overwrite the TASK_STATE_DRAINING state set by a concurrent call to rxe_cleanup_task() or rxe_disable_task().
While state changes are protected by a spinlock, both rxe_cleanup_task() and rxe_disable_task() release the lock while waiting for the task to finish draining in the while(!is_done(task)) loop. The race occurs if do_task() hits its iteration limit and acquires the lock in this window. The cleanup logic may then proceed while the task incorrectly reschedules itself, leading to a potential use-after-free.
This bug was introduced during the migration from tasklets to workqueues, where the special handling for the draining case was lost.
Fix this by restoring the original pre-migration behavior. If the state is TASK_STATE_DRAINING when iterations are exhausted, set cont to 1 to force a new loop iteration. This allows the task to finish its work, so that a subsequent iteration can reach the switch statement and correctly transition the state to TASK_STATE_DRAINED, stopping the task as intended.
Fixes: 9b4b7c1f9f54 ("RDMA/rxe: Add workqueue support for rxe tasks") Reviewed-by: Zhu Yanjun yanjun.zhu@linux.dev Signed-off-by: Gui-Dong Han hanguidong02@gmail.com Link: https://patch.msgid.link/20250919025212.1682087-1-hanguidong02@gmail.com Signed-off-by: Leon Romanovsky leon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/sw/rxe/rxe_task.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/sw/rxe/rxe_task.c b/drivers/infiniband/sw/rxe/rxe_task.c index 80332638d9e3a..be6cd8ce4d97e 100644 --- a/drivers/infiniband/sw/rxe/rxe_task.c +++ b/drivers/infiniband/sw/rxe/rxe_task.c @@ -132,8 +132,12 @@ static void do_task(struct rxe_task *task) * yield the cpu and reschedule the task */ if (!ret) { - task->state = TASK_STATE_IDLE; - resched = 1; + if (task->state != TASK_STATE_DRAINING) { + task->state = TASK_STATE_IDLE; + resched = 1; + } else { + cont = 1; + } goto exit; }