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/mips/lib/bitops.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 162 insertions(+) create mode 100644 arch/mips/lib/bitops.c (limited to 'arch/mips/lib/bitops.c') diff --git a/arch/mips/lib/bitops.c b/arch/mips/lib/bitops.c new file mode 100644 index 000000000..00aee98e9 --- /dev/null +++ b/arch/mips/lib/bitops.c @@ -0,0 +1,162 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (c) 1994-1997, 99, 2000, 06, 07 Ralf Baechle (ralf@linux-mips.org) + * Copyright (c) 1999, 2000 Silicon Graphics, Inc. + */ +#include +#include +#include +#include + + +/** + * __mips_set_bit - Atomically set a bit in memory. This is called by + * set_bit() if it cannot find a faster solution. + * @nr: the bit to set + * @addr: the address to start counting from + */ +void __mips_set_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a |= mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_set_bit); + + +/** + * __mips_clear_bit - Clears a bit in memory. This is called by clear_bit() if + * it cannot find a faster solution. + * @nr: Bit to clear + * @addr: Address to start counting from + */ +void __mips_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a &= ~mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_clear_bit); + + +/** + * __mips_change_bit - Toggle a bit in memory. This is called by change_bit() + * if it cannot find a faster solution. + * @nr: Bit to change + * @addr: Address to start counting from + */ +void __mips_change_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + + mask = 1UL << bit; + raw_local_irq_save(flags); + *a ^= mask; + raw_local_irq_restore(flags); +} +EXPORT_SYMBOL(__mips_change_bit); + + +/** + * __mips_test_and_set_bit_lock - Set a bit and return its old value. This is + * called by test_and_set_bit_lock() if it cannot find a faster solution. + * @nr: Bit to set + * @addr: Address to count from + */ +int __mips_test_and_set_bit_lock(unsigned long nr, + volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a |= mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_set_bit_lock); + + +/** + * __mips_test_and_clear_bit - Clear a bit and return its old value. This is + * called by test_and_clear_bit() if it cannot find a faster solution. + * @nr: Bit to clear + * @addr: Address to count from + */ +int __mips_test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a &= ~mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_clear_bit); + + +/** + * __mips_test_and_change_bit - Change a bit and return its old value. This is + * called by test_and_change_bit() if it cannot find a faster solution. + * @nr: Bit to change + * @addr: Address to count from + */ +int __mips_test_and_change_bit(unsigned long nr, volatile unsigned long *addr) +{ + volatile unsigned long *a = &addr[BIT_WORD(nr)]; + unsigned int bit = nr % BITS_PER_LONG; + unsigned long mask; + unsigned long flags; + int res; + + mask = 1UL << bit; + raw_local_irq_save(flags); + res = (mask & *a) != 0; + *a ^= mask; + raw_local_irq_restore(flags); + return res; +} +EXPORT_SYMBOL(__mips_test_and_change_bit); + +bool __mips_xor_is_negative_byte(unsigned long mask, + volatile unsigned long *addr) +{ + unsigned long flags; + unsigned long data; + + raw_local_irq_save(flags); + data = *addr; + *addr = data ^ mask; + raw_local_irq_restore(flags); + + return (data & BIT(7)) != 0; +} -- cgit v1.3.1