From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- drivers/md/dm-pcache/segment.c | 61 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 drivers/md/dm-pcache/segment.c (limited to 'drivers/md/dm-pcache/segment.c') diff --git a/drivers/md/dm-pcache/segment.c b/drivers/md/dm-pcache/segment.c new file mode 100644 index 000000000..7e9818701 --- /dev/null +++ b/drivers/md/dm-pcache/segment.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include + +#include "pcache_internal.h" +#include "cache_dev.h" +#include "segment.h" + +int segment_copy_to_bio(struct pcache_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off) +{ + struct iov_iter iter; + size_t copied; + void *src; + + iov_iter_bvec(&iter, ITER_DEST, &bio->bi_io_vec[bio->bi_iter.bi_idx], + bio_segments(bio), bio->bi_iter.bi_size); + iter.iov_offset = bio->bi_iter.bi_bvec_done; + if (bio_off) + iov_iter_advance(&iter, bio_off); + + src = segment->data + data_off; + copied = _copy_mc_to_iter(src, data_len, &iter); + if (copied != data_len) + return -EIO; + + return 0; +} + +int segment_copy_from_bio(struct pcache_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off) +{ + struct iov_iter iter; + size_t copied; + void *dst; + + iov_iter_bvec(&iter, ITER_SOURCE, &bio->bi_io_vec[bio->bi_iter.bi_idx], + bio_segments(bio), bio->bi_iter.bi_size); + iter.iov_offset = bio->bi_iter.bi_bvec_done; + if (bio_off) + iov_iter_advance(&iter, bio_off); + + dst = segment->data + data_off; + copied = _copy_from_iter_flushcache(dst, data_len, &iter); + if (copied != data_len) + return -EIO; + pmem_wmb(); + + return 0; +} + +void pcache_segment_init(struct pcache_cache_dev *cache_dev, struct pcache_segment *segment, + struct pcache_segment_init_options *options) +{ + segment->seg_info = options->seg_info; + segment_info_set_type(segment->seg_info, options->type); + + segment->cache_dev = cache_dev; + segment->seg_id = options->seg_id; + segment->data_size = PCACHE_SEG_SIZE - options->data_off; + segment->data = CACHE_DEV_SEGMENT(cache_dev, options->seg_id) + options->data_off; +} -- cgit v1.3.1