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/arc/lib/memset.S | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 arch/arc/lib/memset.S (limited to 'arch/arc/lib/memset.S') diff --git a/arch/arc/lib/memset.S b/arch/arc/lib/memset.S new file mode 100644 index 000000000..9f35960da --- /dev/null +++ b/arch/arc/lib/memset.S @@ -0,0 +1,56 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +#include + +#define SMALL 7 /* Must be at least 6 to deal with alignment/loop issues. */ + +ENTRY_CFI(memset) + mov_s r4,r0 + or r12,r0,r2 + bmsk.f r12,r12,1 + extb_s r1,r1 + asl r3,r1,8 + beq.d .Laligned + or_s r1,r1,r3 + brls r2,SMALL,.Ltiny + add r3,r2,r0 + stb r1,[r3,-1] + bclr_s r3,r3,0 + stw r1,[r3,-2] + bmsk.f r12,r0,1 + add_s r2,r2,r12 + sub.ne r2,r2,4 + stb.ab r1,[r4,1] + and r4,r4,-2 + stw.ab r1,[r4,2] + and r4,r4,-4 +.Laligned: ; This code address should be aligned for speed. + asl r3,r1,16 + lsr.f lp_count,r2,2 + or_s r1,r1,r3 + lpne .Loop_end + st.ab r1,[r4,4] +.Loop_end: + j_s [blink] + + .balign 4 +.Ltiny: + mov.f lp_count,r2 + lpne .Ltiny_end + stb.ab r1,[r4,1] +.Ltiny_end: + j_s [blink] +END_CFI(memset) + +; memzero: @r0 = mem, @r1 = size_t +; memset: @r0 = mem, @r1 = char, @r2 = size_t + +ENTRY_CFI(memzero) + ; adjust bzero args to memset args + mov r2, r1 + mov r1, 0 + b memset ;tail call so need to tinker with blink +END_CFI(memzero) -- cgit v1.3.1