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/uapi/asm-generic/sembuf.h | 45 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 include/uapi/asm-generic/sembuf.h (limited to 'include/uapi/asm-generic/sembuf.h') diff --git a/include/uapi/asm-generic/sembuf.h b/include/uapi/asm-generic/sembuf.h new file mode 100644 index 000000000..f54e48fc9 --- /dev/null +++ b/include/uapi/asm-generic/sembuf.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef __ASM_GENERIC_SEMBUF_H +#define __ASM_GENERIC_SEMBUF_H + +#include +#include + +/* + * The semid64_ds structure for most architectures (though it came from x86_32 + * originally). Note extra padding because this structure is passed back and + * forth between kernel and user space. + * + * semid64_ds was originally meant to be architecture specific, but + * everyone just ended up making identical copies without specific + * optimizations, so we may just as well all use the same one. + * + * 64 bit architectures use a 64-bit long time field here, while + * 32 bit architectures have a pair of unsigned long values. + * + * On big-endian systems, the padding is in the wrong place for + * historic reasons, so user space has to reconstruct a time_t + * value using + * + * user_semid_ds.sem_otime = kernel_semid64_ds.sem_otime + + * ((long long)kernel_semid64_ds.sem_otime_high << 32) + * + * Pad space is left for 2 miscellaneous 32-bit values + */ +struct semid64_ds { + struct ipc64_perm sem_perm; /* permissions .. see ipc.h */ +#if __BITS_PER_LONG == 64 + long sem_otime; /* last semop time */ + long sem_ctime; /* last change time */ +#else + unsigned long sem_otime; /* last semop time */ + unsigned long sem_otime_high; + unsigned long sem_ctime; /* last change time */ + unsigned long sem_ctime_high; +#endif + unsigned long sem_nsems; /* no. of semaphores in array */ + unsigned long __unused3; + unsigned long __unused4; +}; + +#endif /* __ASM_GENERIC_SEMBUF_H */ -- cgit v1.3.1