Under memory pressure, the qede driver encounters NULL pointer dereferences when processing TPA continuation fragments because: 1. qede_fill_frag_skb() does not validate the page pointer before use 2. qede_tpa_end() checks error state AFTER calling qede_fill_frag_skb() The crash occurs when: 1. System experiences memory pressure (GFP_ATOMIC allocations fail) 2. qede_alloc_rx_buffer() returns -ENOMEM, leaving sw_rx_data->data NULL 3. qede_tpa_start() sets QEDE_AGG_STATE_ERROR on SKB allocation failure 4. Hardware delivers TPA_CONT and TPA_END events for this aggregation 5. qede_tpa_end() calls qede_fill_frag_skb() before checking error state 6. qede_fill_frag_skb() accesses NULL pointer in skb_fill_page_desc() 7. Kernel panics with NULL pointer dereference Example crash from production system: BUG: unable to handle kernel NULL pointer dereference at 0x8 RIP: qede_fill_frag_skb+0x96/0x430 [qede] Call Trace: qede_rx_int+0xb06/0x1de0 qede_poll+0x2f4/0x6c0 __napi_poll+0x2d/0x130 Observed on HPE Synergy 480 Gen11 running RHEL 8.10 (4.18.0-553.134.1.el8_10.x86_64), but the vulnerable code path exists in mainline. Fix by: 1. Adding NULL page validation in qede_fill_frag_skb() before dereferencing. 2. Checking error state EARLY in qede_tpa_end() and qede_tpa_cont() before processing fragments. 3. Ensuring NULL buffer descriptors are consumed rather than recycled to prevent NULL pointers from re-entering the active Rx ring. 4. Correcting buffer capacity tracking (rxq->filled_buffers) when dropping empty descriptors to avoid Rx ring starvation. 5. Validating uninitialized buffers before reusing them in error paths to prevent DMA and memory leaks. Fixes: 55482edc25f0 ("qede: Add slowpath/fastpath support and enable hardware GRO") Cc: stable@vger.kernel.org Signed-off-by: Vaibhav Nagare --- v3: Addressed AI review feedback: - Fixed out-of-bounds array read by correcting logical AND condition order in qede_tpa_end() loop. - Decremented rxq->filled_buffers when dropping NULL descriptors to prevent Rx ring starvation. - Checked rx_bd->data validity before recycling BDs in TPA error loops to prevent re-injecting NULL pointers into the active ring. - Fixed qede_tpa_end() error jump to prevent qede_reuse_page() from recycling uninitialized buffers and leaking DMA mappings. - Moved version history below the '---' marker per subsystem guidelines. v2: Addressed AI review feedback from Simon Horman: - Added net_ratelimit() to prevent printk storm in NAPI fast path - Fixed NULL buffer recycling: check if page is valid before recycling, otherwise just consume the BD to prevent NULL from re-entering the ring - Added proper cleanup in qede_tpa_end() before early exit to prevent memory leaks and ring desynchronization (DMA unmap + BD recycling) v1: https://lore.kernel.org/netdev/20260709044704.141507-1-vnagare@redhat.com/ drivers/net/ethernet/qlogic/qede/qede_fp.c | 59 ++++++++++++++++++++-- 1 file changed, 54 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/qlogic/qede/qede_fp.c b/drivers/net/ethernet/qlogic/qede/qede_fp.c index 33e18bb69774..dd6032200f52 100644 --- a/drivers/net/ethernet/qlogic/qede/qede_fp.c +++ b/drivers/net/ethernet/qlogic/qede/qede_fp.c @@ -670,13 +670,23 @@ static int qede_fill_frag_skb(struct qede_dev *edev, NUM_RX_BDS_MAX]; struct qede_agg_info *tpa_info = &rxq->tpa_info[tpa_agg_index]; struct sk_buff *skb = tpa_info->skb; + struct page *page = current_bd->data; if (unlikely(tpa_info->state != QEDE_AGG_STATE_START)) goto out; + /* Avoid NULL pointer dereference when under severe memory pressure */ + if (unlikely(!page)) { + if (net_ratelimit()) + DP_NOTICE(edev, + "Failed to allocate RX buffer for TPA agg %u\n", + tpa_agg_index); + goto out; + } + /* Add one frag and update the appropriate fields in the skb */ skb_fill_page_desc(skb, tpa_info->frag_id++, - current_bd->data, + page, current_bd->page_offset + rxq->rx_headroom, len_on_bd); @@ -684,7 +694,7 @@ static int qede_fill_frag_skb(struct qede_dev *edev, /* Incr page ref count to reuse on allocation failure * so that it doesn't get freed while freeing SKB. */ - page_ref_inc(current_bd->data); + page_ref_inc(page); goto out; } @@ -698,8 +708,12 @@ static int qede_fill_frag_skb(struct qede_dev *edev, out: tpa_info->state = QEDE_AGG_STATE_ERROR; - qede_recycle_rx_bd_ring(rxq, 1); - + if (current_bd->data) { + qede_recycle_rx_bd_ring(rxq, 1); + } else { + qede_rx_bd_ring_consume(rxq); + rxq->filled_buffers--; + } return -ENOMEM; } @@ -959,8 +973,24 @@ static inline void qede_tpa_cont(struct qede_dev *edev, struct qede_rx_queue *rxq, struct eth_fast_path_rx_tpa_cont_cqe *cqe) { + struct qede_agg_info *tpa_info = &rxq->tpa_info[cqe->tpa_agg_index]; int i; + /* Don't process fragments if TPA start failed */ + if (unlikely(tpa_info->state != QEDE_AGG_STATE_START)) { + for (i = 0; i < ARRAY_SIZE(cqe->len_list) && cqe->len_list[i]; i++) { + struct sw_rx_data *rx_bd = &rxq->sw_rx_ring[rxq->sw_rx_cons & + NUM_RX_BDS_MAX]; + if (likely(rx_bd->data)) { + qede_recycle_rx_bd_ring(rxq, 1); + } else { + qede_rx_bd_ring_consume(rxq); + rxq->filled_buffers--; + } + } + return; + } + for (i = 0; i < ARRAY_SIZE(cqe->len_list) && cqe->len_list[i]; i++) qede_fill_frag_skb(edev, rxq, cqe->tpa_agg_index, le16_to_cpu(cqe->len_list[i])); @@ -982,6 +1012,22 @@ static int qede_tpa_end(struct qede_dev *edev, tpa_info = &rxq->tpa_info[cqe->tpa_agg_index]; skb = tpa_info->skb; + /* Drop the packet if TPA start failed */ + if (unlikely(tpa_info->state != QEDE_AGG_STATE_START || !skb)) { + /* Recycle BDs from cqe->len_list to keep ring synchronized */ + for (i = 0; i < ARRAY_SIZE(cqe->len_list) && cqe->len_list[i]; i++) { + struct sw_rx_data *rx_bd = &rxq->sw_rx_ring[rxq->sw_rx_cons & + NUM_RX_BDS_MAX]; + if (likely(rx_bd->data)) { + qede_recycle_rx_bd_ring(rxq, 1); + } else { + qede_rx_bd_ring_consume(rxq); + rxq->filled_buffers--; + } + } + goto err; + } + if (tpa_info->buffer.page_offset == PAGE_SIZE) dma_unmap_page(rxq->dev, tpa_info->buffer.mapping, PAGE_SIZE, rxq->data_direction); @@ -1023,8 +1069,11 @@ static int qede_tpa_end(struct qede_dev *edev, err: tpa_info->state = QEDE_AGG_STATE_NONE; - if (tpa_info->tpa_start_fail) { + if (likely(tpa_info->buffer.data)) { qede_reuse_page(rxq, &tpa_info->buffer); + } else if (tpa_info->buffer.page_offset == PAGE_SIZE) { + dma_unmap_page(rxq->dev, tpa_info->buffer.mapping, + PAGE_SIZE, rxq->data_direction); tpa_info->tpa_start_fail = false; } -- 2.54.0