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 --- include/asm-generic/atomic.h | 133 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 include/asm-generic/atomic.h (limited to 'include/asm-generic/atomic.h') diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h new file mode 100644 index 000000000..22142c71d --- /dev/null +++ b/include/asm-generic/atomic.h @@ -0,0 +1,133 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Generic C implementation of atomic counter operations. Do not include in + * machine independent code. + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ +#ifndef __ASM_GENERIC_ATOMIC_H +#define __ASM_GENERIC_ATOMIC_H + +#include +#include + +#ifdef CONFIG_SMP + +/* we can build all atomic primitives from cmpxchg */ + +#define ATOMIC_OP(op, c_op) \ +static inline void generic_atomic_##op(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ +} + +#define ATOMIC_OP_RETURN(op, c_op) \ +static inline int generic_atomic_##op##_return(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ + \ + return c c_op i; \ +} + +#define ATOMIC_FETCH_OP(op, c_op) \ +static inline int generic_atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ + \ + return c; \ +} + +#else + +#include + +#define ATOMIC_OP(op, c_op) \ +static inline void generic_atomic_##op(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + \ + raw_local_irq_save(flags); \ + v->counter = v->counter c_op i; \ + raw_local_irq_restore(flags); \ +} + +#define ATOMIC_OP_RETURN(op, c_op) \ +static inline int generic_atomic_##op##_return(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + int ret; \ + \ + raw_local_irq_save(flags); \ + ret = (v->counter = v->counter c_op i); \ + raw_local_irq_restore(flags); \ + \ + return ret; \ +} + +#define ATOMIC_FETCH_OP(op, c_op) \ +static inline int generic_atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + int ret; \ + \ + raw_local_irq_save(flags); \ + ret = v->counter; \ + v->counter = v->counter c_op i; \ + raw_local_irq_restore(flags); \ + \ + return ret; \ +} + +#endif /* CONFIG_SMP */ + +ATOMIC_OP_RETURN(add, +) +ATOMIC_OP_RETURN(sub, -) + +ATOMIC_FETCH_OP(add, +) +ATOMIC_FETCH_OP(sub, -) +ATOMIC_FETCH_OP(and, &) +ATOMIC_FETCH_OP(or, |) +ATOMIC_FETCH_OP(xor, ^) + +ATOMIC_OP(add, +) +ATOMIC_OP(sub, -) +ATOMIC_OP(and, &) +ATOMIC_OP(or, |) +ATOMIC_OP(xor, ^) + +#undef ATOMIC_FETCH_OP +#undef ATOMIC_OP_RETURN +#undef ATOMIC_OP + +#define arch_atomic_add_return generic_atomic_add_return +#define arch_atomic_sub_return generic_atomic_sub_return + +#define arch_atomic_fetch_add generic_atomic_fetch_add +#define arch_atomic_fetch_sub generic_atomic_fetch_sub +#define arch_atomic_fetch_and generic_atomic_fetch_and +#define arch_atomic_fetch_or generic_atomic_fetch_or +#define arch_atomic_fetch_xor generic_atomic_fetch_xor + +#define arch_atomic_add generic_atomic_add +#define arch_atomic_sub generic_atomic_sub +#define arch_atomic_and generic_atomic_and +#define arch_atomic_or generic_atomic_or +#define arch_atomic_xor generic_atomic_xor + +#define arch_atomic_read(v) READ_ONCE((v)->counter) +#define arch_atomic_set(v, i) WRITE_ONCE(((v)->counter), (i)) + +#endif /* __ASM_GENERIC_ATOMIC_H */ -- cgit v1.3.1