From dcca1662727220d18fa351097ddff33f95f516c5 Mon Sep 17 00:00:00 2001 From: Hongbo Yao Date: Mon, 7 Jan 2019 10:22:07 +0800 Subject: [PATCH] nvme-pci: fix out of bounds access in nvme_cqe_pending There is an out of bounds array access in nvme_cqe_peding(). When enable irq_thread for nvme interrupt, there is racing between the nvmeq->cq_head updating and reading. nvmeq->cq_head is updated in nvme_update_cq_head(), if nvmeq->cq_head equals nvmeq->q_depth and before its value set to zero, nvme_cqe_pending() uses its value as an array index, the index will be out of bounds. Signed-off-by: Hongbo Yao [hch: slight coding style update] Signed-off-by: Christoph Hellwig --- drivers/nvme/host/pci.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index f891eb57f263..3f53a2c3042d 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -1020,9 +1020,11 @@ static void nvme_complete_cqes(struct nvme_queue *nvmeq, u16 start, u16 end) static inline void nvme_update_cq_head(struct nvme_queue *nvmeq) { - if (++nvmeq->cq_head == nvmeq->q_depth) { + if (nvmeq->cq_head == nvmeq->q_depth - 1) { nvmeq->cq_head = 0; nvmeq->cq_phase = !nvmeq->cq_phase; + } else { + nvmeq->cq_head++; } } -- 2.11.0