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/lib/string.S | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 arch/powerpc/lib/string.S (limited to 'arch/powerpc/lib/string.S') diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S new file mode 100644 index 000000000..c3f5e7d31 --- /dev/null +++ b/arch/powerpc/lib/string.S @@ -0,0 +1,43 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * String handling functions for PowerPC. + * + * Copyright (C) 1996 Paul Mackerras. + */ +#include +#include +#include + + .text + +_GLOBAL(strncmp) + PPC_LCMPI 0,r5,0 + beq- 2f + mtctr r5 + addi r5,r3,-1 + addi r4,r4,-1 + .balign IFETCH_ALIGN_BYTES +1: lbzu r3,1(r5) + cmpwi 1,r3,0 + lbzu r0,1(r4) + subf. r3,r0,r3 + beqlr 1 + bdnzt eq,1b + blr +2: li r3,0 + blr +EXPORT_SYMBOL(strncmp) + +_GLOBAL(memchr) + PPC_LCMPI 0,r5,0 + beq- 2f + mtctr r5 + addi r3,r3,-1 + .balign IFETCH_ALIGN_BYTES +1: lbzu r0,1(r3) + cmpw 0,r0,r4 + bdnzf 2,1b + beqlr +2: li r3,0 + blr +EXPORT_SYMBOL(memchr) -- cgit v1.3.1