Under memory pressure, the qede driver encounters NULL pointer dereferences when processing TPA continuation fragments. As identified by Jakub Kicinski, commit 8a8633978b84 ("qede: Add build_skb() support.") accidentally dropped the assignment of tpa_info->buffer.data in qede_tpa_start(). When memory pressure causes an SKB allocation failure in qede_tpa_start(), the driver sets tpa_start_fail = true and attempts to recycle the physical page later in qede_tpa_end(). However, because buffer.data was left uninitialized (NULL), qede_reuse_page() pushes a "ghost" page (valid mapping but NULL data pointer) back into the active Rx ring. The next time the hardware uses this descriptor, it passes a NULL page to qede_fill_frag_skb(), causing a kernel panic. 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 the root cause by: 1. Restoring the tpa_info->buffer.data assignment in qede_tpa_start(). 2. Reverting the error recovery block in qede_tpa_end() to rely on tpa_start_fail, which safely recycles the page without causing double DMA unmaps. Additionally, harden the surrounding TPA flow: 3. Add NULL page validation in qede_fill_frag_skb() before dereferencing. 4. Correct bounds checking logic in TPA error loops (evaluating bounds before reading the array elements to prevent out-of-bounds reads). 5. Check error state early in qede_tpa_end() and qede_tpa_cont() before processing fragments. 6. Ensure NULL buffer descriptors are consumed rather than recycled, and correct buffer capacity tracking (rxq->filled_buffers--) to avoid Rx ring starvation. Fixes: 8a8633978b84 ("qede: Add build_skb() support.") Suggested-by: Jakub Kicinski Cc: stable@vger.kernel.org Signed-off-by: Vaibhav Nagare --- v4: Fix err: label handling as identified by Jakub Kicinski: - Restored tpa_info->buffer.data assignment in qede_tpa_start(), which was dropped by commit 8a8633978b84 - Reverted err: label in qede_tpa_end() to use tpa_start_fail flag instead of buffer.data check (ownership semantics) - Updated Fixes: tag to 8a8633978b84 - Added Suggested-by: Jakub Kicinski v3: Addressed additional AI review feedback: - Fixed NULL pointer recycling in qede_tpa_cont() and qede_tpa_end() - Fixed array bounds check order in TPA error loops - Moved version notes after --- per Markus Elfring feedback - Resent as independent thread per netdev-bot feedback v2: Addressed AI review feedback from Simon Horman: - Added net_ratelimit() to prevent printk storm in NAPI fast path - Fixed NULL buffer recycling in qede_fill_frag_skb() - Added proper cleanup in qede_tpa_end() early exit path v1: https://lore.kernel.org/netdev/20260709044704.141507-1-vnagare@redhat.com/ drivers/net/ethernet/qlogic/qede/qede_fp.c | 56 ++++++++++++++++++++-- 1 file changed, 51 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..bf0448b035b4 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; } @@ -845,7 +859,7 @@ static void qede_tpa_start(struct qede_dev *edev, pad, false); tpa_info->buffer.page_offset = sw_rx_data_cons->page_offset; tpa_info->buffer.mapping = sw_rx_data_cons->mapping; - + tpa_info->buffer.data = sw_rx_data_cons->data; if (unlikely(!tpa_info->skb)) { DP_NOTICE(edev, "Failed to allocate SKB for gro\n"); @@ -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])); @@ -986,6 +1016,22 @@ static int qede_tpa_end(struct qede_dev *edev, dma_unmap_page(rxq->dev, tpa_info->buffer.mapping, PAGE_SIZE, rxq->data_direction); + /* 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; + } + 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])); -- 2.54.0