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 --- lib/crypto/mpi/mpiutil.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 152 insertions(+) create mode 100644 lib/crypto/mpi/mpiutil.c (limited to 'lib/crypto/mpi/mpiutil.c') diff --git a/lib/crypto/mpi/mpiutil.c b/lib/crypto/mpi/mpiutil.c new file mode 100644 index 000000000..f4faf7c90 --- /dev/null +++ b/lib/crypto/mpi/mpiutil.c @@ -0,0 +1,152 @@ +/* mpiutil.ac - Utility functions for MPI + * Copyright (C) 1998, 1999 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * GnuPG is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * GnuPG is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ + +#include + +#include "mpi-internal.h" + +/**************** + * Note: It was a bad idea to use the number of limbs to allocate + * because on a alpha the limbs are large but we normally need + * integers of n bits - So we should change this to bits (or bytes). + * + * But mpi_alloc is used in a lot of places :-) + */ +MPI mpi_alloc(unsigned nlimbs) +{ + MPI a; + + a = kmalloc_obj(*a); + if (!a) + return a; + + if (nlimbs) { + a->d = mpi_alloc_limb_space(nlimbs); + if (!a->d) { + kfree(a); + return NULL; + } + } else { + a->d = NULL; + } + + a->alloced = nlimbs; + a->nlimbs = 0; + a->sign = 0; + a->flags = 0; + a->nbits = 0; + return a; +} +EXPORT_SYMBOL_GPL(mpi_alloc); + +mpi_ptr_t mpi_alloc_limb_space(unsigned nlimbs) +{ + size_t len = nlimbs * sizeof(mpi_limb_t); + + if (!len) + return NULL; + + return kmalloc(len, GFP_KERNEL); +} + +void mpi_free_limb_space(mpi_ptr_t a) +{ + if (!a) + return; + + kfree_sensitive(a); +} + +void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs) +{ + mpi_free_limb_space(a->d); + a->d = ap; + a->alloced = nlimbs; +} + +/**************** + * Resize the array of A to NLIMBS. the additional space is cleared + * (set to 0) [done by m_realloc()] + */ +int mpi_resize(MPI a, unsigned nlimbs) +{ + void *p; + + if (nlimbs <= a->alloced) + return 0; /* no need to do it */ + + if (a->d) { + p = kzalloc_objs(mpi_limb_t, nlimbs); + if (!p) + return -ENOMEM; + memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t)); + kfree_sensitive(a->d); + a->d = p; + } else { + a->d = kzalloc_objs(mpi_limb_t, nlimbs); + if (!a->d) + return -ENOMEM; + } + a->alloced = nlimbs; + return 0; +} + +void mpi_free(MPI a) +{ + if (!a) + return; + + if (a->flags & 4) + kfree_sensitive(a->d); + else + mpi_free_limb_space(a->d); + + if (a->flags & ~7) + pr_info("invalid flag value in mpi\n"); + kfree(a); +} +EXPORT_SYMBOL_GPL(mpi_free); + +/**************** + * Note: This copy function should not interpret the MPI + * but copy it transparently. + */ +MPI mpi_copy(MPI a) +{ + int i; + MPI b; + + if (a) { + b = mpi_alloc(a->nlimbs); + if (!b) + return NULL; + b->nlimbs = a->nlimbs; + b->sign = a->sign; + b->flags = a->flags; + b->flags &= ~(16|32); /* Reset the immutable and constant flags. */ + for (i = 0; i < b->nlimbs; i++) + b->d[i] = a->d[i]; + } else + b = NULL; + return b; +} + +MODULE_DESCRIPTION("Multiprecision maths library"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1