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/strcmp.S | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 arch/arc/lib/strcmp.S (limited to 'arch/arc/lib/strcmp.S') diff --git a/arch/arc/lib/strcmp.S b/arch/arc/lib/strcmp.S new file mode 100644 index 000000000..b20c98fb3 --- /dev/null +++ b/arch/arc/lib/strcmp.S @@ -0,0 +1,93 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +/* This is optimized primarily for the ARC700. + It would be possible to speed up the loops by one cycle / word + respective one cycle / byte by forcing double source 1 alignment, unrolling + by a factor of two, and speculatively loading the second word / byte of + source 1; however, that would increase the overhead for loop setup / finish, + and strcmp might often terminate early. */ + +#include + +ENTRY_CFI(strcmp) + or r2,r0,r1 + bmsk_s r2,r2,1 + brne r2,0,.Lcharloop + mov_s r12,0x01010101 + ror r5,r12 +.Lwordloop: + ld.ab r2,[r0,4] + ld.ab r3,[r1,4] + nop_s + sub r4,r2,r12 + bic r4,r4,r2 + and r4,r4,r5 + brne r4,0,.Lfound0 + breq r2,r3,.Lwordloop +#ifdef __LITTLE_ENDIAN__ + xor r0,r2,r3 ; mask for difference + sub_s r1,r0,1 + bic_s r0,r0,r1 ; mask for least significant difference bit + sub r1,r5,r0 + xor r0,r5,r1 ; mask for least significant difference byte + and_s r2,r2,r0 + and_s r3,r3,r0 +#endif /* LITTLE ENDIAN */ + cmp_s r2,r3 + mov_s r0,1 + j_s.d [blink] + bset.lo r0,r0,31 + + .balign 4 +#ifdef __LITTLE_ENDIAN__ +.Lfound0: + xor r0,r2,r3 ; mask for difference + or r0,r0,r4 ; or in zero indicator + sub_s r1,r0,1 + bic_s r0,r0,r1 ; mask for least significant difference bit + sub r1,r5,r0 + xor r0,r5,r1 ; mask for least significant difference byte + and_s r2,r2,r0 + and_s r3,r3,r0 + sub.f r0,r2,r3 + mov.hi r0,1 + j_s.d [blink] + bset.lo r0,r0,31 +#else /* BIG ENDIAN */ + /* The zero-detection above can mis-detect 0x01 bytes as zeroes + because of carry-propagateion from a lower significant zero byte. + We can compensate for this by checking that bit0 is zero. + This compensation is not necessary in the step where we + get a low estimate for r2, because in any affected bytes + we already have 0x00 or 0x01, which will remain unchanged + when bit 7 is cleared. */ + .balign 4 +.Lfound0: + lsr r0,r4,8 + lsr_s r1,r2 + bic_s r2,r2,r0 ; get low estimate for r2 and get ... + bic_s r0,r0,r1 ; + or_s r3,r3,r0 ; ... high estimate r3 so that r2 > r3 will ... + cmp_s r3,r2 ; ... be independent of trailing garbage + or_s r2,r2,r0 ; likewise for r3 > r2 + bic_s r3,r3,r0 + rlc r0,0 ; r0 := r2 > r3 ? 1 : 0 + cmp_s r2,r3 + j_s.d [blink] + bset.lo r0,r0,31 +#endif /* ENDIAN */ + + .balign 4 +.Lcharloop: + ldb.ab r2,[r0,1] + ldb.ab r3,[r1,1] + nop_s + breq r2,0,.Lcmpend + breq r2,r3,.Lcharloop +.Lcmpend: + j_s.d [blink] + sub r0,r2,r3 +END_CFI(strcmp) -- cgit v1.3.1