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 --- tools/lib/slab.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 tools/lib/slab.c (limited to 'tools/lib/slab.c') diff --git a/tools/lib/slab.c b/tools/lib/slab.c new file mode 100644 index 000000000..981a21404 --- /dev/null +++ b/tools/lib/slab.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include + +#include +#include +#include +#include + +int kmalloc_nr_allocated; +int kmalloc_verbose; + +void *kmalloc(size_t size, gfp_t gfp) +{ + void *ret; + + if (!(gfp & __GFP_DIRECT_RECLAIM)) + return NULL; + + ret = malloc(size); + uatomic_inc(&kmalloc_nr_allocated); + if (kmalloc_verbose) + printf("Allocating %p from malloc\n", ret); + if (gfp & __GFP_ZERO) + memset(ret, 0, size); + return ret; +} + +void kfree(void *p) +{ + if (!p) + return; + uatomic_dec(&kmalloc_nr_allocated); + if (kmalloc_verbose) + printf("Freeing %p to malloc\n", p); + free(p); +} + +void *kmalloc_array(size_t n, size_t size, gfp_t gfp) +{ + void *ret; + + if (!(gfp & __GFP_DIRECT_RECLAIM)) + return NULL; + + ret = calloc(n, size); + uatomic_inc(&kmalloc_nr_allocated); + if (kmalloc_verbose) + printf("Allocating %p from calloc\n", ret); + if (gfp & __GFP_ZERO) + memset(ret, 0, n * size); + return ret; +} -- cgit v1.3.1