From 907a56ab3eb8a58500a58daa76087f17bb2b6826 Mon Sep 17 00:00:00 2001 From: Alexandra Winter Date: Wed, 2 Sep 2026 16:37:33 +0200 Subject: [PATCH] s390/ism: folio_put() after error dmb->cpu_addr was allocated via folio_alloc(). Use folio_put() instead of kfree() in the error exit of ism_alloc_dmb() to avoid slab allocator corruption. While at it, reset dmb->cpu_addr after folio_put to avoid unintentional UAF by future callers. Fixes: 83781384a96b ("s390/ism: Properly fix receive message buffer allocation") Signed-off-by: Alexandra Winter Reviewed-by: Gerd Bayer Link: https://patch.msgid.link/20260902143733.433574-1-wintera@linux.ibm.com Signed-off-by: Jakub Kicinski --- drivers/s390/net/ism_drv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c index 242da20f27e0..035b233abb4e 100644 --- a/drivers/s390/net/ism_drv.c +++ b/drivers/s390/net/ism_drv.c @@ -231,6 +231,7 @@ static void ism_free_dmb(struct ism_dev *ism, struct dibs_dmb *dmb) dma_unmap_page(&ism->pdev->dev, dmb->dma_addr, dmb->dmb_len, DMA_FROM_DEVICE); folio_put(virt_to_folio(dmb->cpu_addr)); + dmb->cpu_addr = NULL; } static int ism_alloc_dmb(struct ism_dev *ism, struct dibs_dmb *dmb) @@ -274,7 +275,8 @@ static int ism_alloc_dmb(struct ism_dev *ism, struct dibs_dmb *dmb) return 0; out_free: - kfree(dmb->cpu_addr); + folio_put(folio); + dmb->cpu_addr = NULL; out_bit: clear_bit(dmb->idx, ism->sba_bitmap); return rc;