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/mpi-cmp.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 lib/crypto/mpi/mpi-cmp.c (limited to 'lib/crypto/mpi/mpi-cmp.c') diff --git a/lib/crypto/mpi/mpi-cmp.c b/lib/crypto/mpi/mpi-cmp.c new file mode 100644 index 000000000..b42929296 --- /dev/null +++ b/lib/crypto/mpi/mpi-cmp.c @@ -0,0 +1,74 @@ +/* mpi-cmp.c - MPI functions + * 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" + +int mpi_cmp_ui(MPI u, unsigned long v) +{ + mpi_limb_t limb = v; + + mpi_normalize(u); + if (u->nlimbs == 0) { + if (v == 0) + return 0; + else + return -1; + } + if (u->sign) + return -1; + if (u->nlimbs > 1) + return 1; + + if (u->d[0] == limb) + return 0; + else if (u->d[0] > limb) + return 1; + else + return -1; +} +EXPORT_SYMBOL_GPL(mpi_cmp_ui); + +int mpi_cmp(MPI u, MPI v) +{ + mpi_size_t usize, vsize; + int cmp; + + mpi_normalize(u); + mpi_normalize(v); + usize = u->nlimbs; + vsize = v->nlimbs; + if (!u->sign && v->sign) + return 1; + if (u->sign && !v->sign) + return -1; + if (usize != vsize && !u->sign && !v->sign) + return usize - vsize; + if (usize != vsize && u->sign && v->sign) + return vsize - usize; + if (!usize) + return 0; + cmp = mpihelp_cmp(u->d, v->d, usize); + if (u->sign) + return -cmp; + return cmp; +} +EXPORT_SYMBOL_GPL(mpi_cmp); -- cgit v1.3.1