From 59c3d55a946cacdb4181600723c20ac4f4c20c84 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Sun, 5 Apr 2026 06:52:41 +0100 Subject: net: lan966x: fix use-after-free and leak in lan966x_fdma_reload() When lan966x_fdma_reload() fails to allocate new RX buffers, the restore path restarts DMA using old descriptors whose pages were already freed via lan966x_fdma_rx_free_pages(). Since page_pool_put_full_page() can release pages back to the buddy allocator, the hardware may DMA into memory now owned by other kernel subsystems. Additionally, on the restore path, the newly created page pool (if allocation partially succeeded) is overwritten without being destroyed, leaking it. Fix both issues by deferring the release of old pages until after the new allocation succeeds. Save the old page array before the allocation so old pages can be freed on the success path. On the failure path, the old descriptors, pages and page pool are all still valid, making the restore safe. Also ensure the restore path re-enables NAPI and wakes the netdev, matching the success path. Fixes: 89ba464fcf54 ("net: lan966x: refactor buffer reload function") Cc: stable@vger.kernel.org Signed-off-by: David Carlier Link: https://patch.msgid.link/20260405055241.35767-4-devnexen@gmail.com Signed-off-by: Paolo Abeni --- .../net/ethernet/microchip/lan966x/lan966x_fdma.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c index 10773fe93d4d7..f8ce735a7fc09 100644 --- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c @@ -812,9 +812,15 @@ static int lan966x_qsys_sw_status(struct lan966x *lan966x) static int lan966x_fdma_reload(struct lan966x *lan966x, int new_mtu) { + struct page *(*old_pages)[FDMA_RX_DCB_MAX_DBS]; struct page_pool *page_pool; struct fdma fdma_rx_old; - int err; + int err, i, j; + + old_pages = kmemdup(lan966x->rx.page, sizeof(lan966x->rx.page), + GFP_KERNEL); + if (!old_pages) + return -ENOMEM; /* Store these for later to free them */ memcpy(&fdma_rx_old, &lan966x->rx.fdma, sizeof(struct fdma)); @@ -825,7 +831,6 @@ static int lan966x_fdma_reload(struct lan966x *lan966x, int new_mtu) lan966x_fdma_stop_netdev(lan966x); lan966x_fdma_rx_disable(&lan966x->rx); - lan966x_fdma_rx_free_pages(&lan966x->rx); lan966x->rx.page_order = round_up(new_mtu, PAGE_SIZE) / PAGE_SIZE - 1; lan966x->rx.max_mtu = new_mtu; err = lan966x_fdma_rx_alloc(&lan966x->rx); @@ -833,6 +838,11 @@ static int lan966x_fdma_reload(struct lan966x *lan966x, int new_mtu) goto restore; lan966x_fdma_rx_start(&lan966x->rx); + for (i = 0; i < fdma_rx_old.n_dcbs; ++i) + for (j = 0; j < fdma_rx_old.n_dbs; ++j) + page_pool_put_full_page(page_pool, + old_pages[i][j], false); + fdma_free_coherent(lan966x->dev, &fdma_rx_old); page_pool_destroy(page_pool); @@ -840,12 +850,17 @@ static int lan966x_fdma_reload(struct lan966x *lan966x, int new_mtu) lan966x_fdma_wakeup_netdev(lan966x); napi_enable(&lan966x->napi); - return err; + kfree(old_pages); + return 0; restore: lan966x->rx.page_pool = page_pool; memcpy(&lan966x->rx.fdma, &fdma_rx_old, sizeof(struct fdma)); lan966x_fdma_rx_start(&lan966x->rx); + lan966x_fdma_wakeup_netdev(lan966x); + napi_enable(&lan966x->napi); + + kfree(old_pages); return err; } -- cgit v1.2.3