From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- arch/powerpc/sysdev/grackle.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 arch/powerpc/sysdev/grackle.c (limited to 'arch/powerpc/sysdev/grackle.c') diff --git a/arch/powerpc/sysdev/grackle.c b/arch/powerpc/sysdev/grackle.c new file mode 100644 index 000000000..7dce8278b --- /dev/null +++ b/arch/powerpc/sysdev/grackle.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Functions for setting up and using a MPC106 northbridge + * Extracted from arch/powerpc/platforms/powermac/pci.c. + * + * Copyright (C) 2003 Benjamin Herrenschmuidt (benh@kernel.crashing.org) + * Copyright (C) 1997 Paul Mackerras (paulus@samba.org) + */ +#include +#include +#include +#include + +#include +#include +#include + +#define GRACKLE_CFA(b, d, o) (0x80 | ((b) << 8) | ((d) << 16) \ + | (((o) & ~3) << 24)) + +#define GRACKLE_PICR1_LOOPSNOOP 0x00000010 + +static inline void grackle_set_loop_snoop(struct pci_controller *bp, int enable) +{ + unsigned int val; + + out_be32(bp->cfg_addr, GRACKLE_CFA(0, 0, 0xa8)); + val = in_le32(bp->cfg_data); + val = enable? (val | GRACKLE_PICR1_LOOPSNOOP) : + (val & ~GRACKLE_PICR1_LOOPSNOOP); + out_be32(bp->cfg_addr, GRACKLE_CFA(0, 0, 0xa8)); + out_le32(bp->cfg_data, val); + (void)in_le32(bp->cfg_data); +} + +void __init setup_grackle(struct pci_controller *hose) +{ + setup_indirect_pci(hose, 0xfec00000, 0xfee00000, 0); + if (of_machine_is_compatible("PowerMac1,1")) + pci_add_flags(PCI_REASSIGN_ALL_BUS); + if (of_machine_is_compatible("AAPL,PowerBook1998")) + grackle_set_loop_snoop(hose, 1); +} -- cgit v1.3.1