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.h | 74 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 drivers/md/dm-pcache/segment.h (limited to 'drivers/md/dm-pcache/segment.h') diff --git a/drivers/md/dm-pcache/segment.h b/drivers/md/dm-pcache/segment.h new file mode 100644 index 000000000..deca1ddcb --- /dev/null +++ b/drivers/md/dm-pcache/segment.h @@ -0,0 +1,74 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _PCACHE_SEGMENT_H +#define _PCACHE_SEGMENT_H + +#include +#include + +#include "pcache_internal.h" + +struct pcache_segment_info { + struct pcache_meta_header header; + __u32 flags; + __u32 next_seg; +}; + +#define PCACHE_SEG_INFO_FLAGS_HAS_NEXT BIT(0) + +#define PCACHE_SEG_INFO_FLAGS_TYPE_MASK GENMASK(4, 1) +#define PCACHE_SEGMENT_TYPE_CACHE_DATA 1 + +static inline bool segment_info_has_next(struct pcache_segment_info *seg_info) +{ + return (seg_info->flags & PCACHE_SEG_INFO_FLAGS_HAS_NEXT); +} + +static inline void segment_info_set_type(struct pcache_segment_info *seg_info, u8 type) +{ + seg_info->flags &= ~PCACHE_SEG_INFO_FLAGS_TYPE_MASK; + seg_info->flags |= FIELD_PREP(PCACHE_SEG_INFO_FLAGS_TYPE_MASK, type); +} + +static inline u8 segment_info_get_type(struct pcache_segment_info *seg_info) +{ + return FIELD_GET(PCACHE_SEG_INFO_FLAGS_TYPE_MASK, seg_info->flags); +} + +struct pcache_segment_pos { + struct pcache_segment *segment; /* Segment associated with the position */ + u32 off; /* Offset within the segment */ +}; + +struct pcache_segment_init_options { + u8 type; + u32 seg_id; + u32 data_off; + + struct pcache_segment_info *seg_info; +}; + +struct pcache_segment { + struct pcache_cache_dev *cache_dev; + + void *data; + u32 data_size; + u32 seg_id; + + struct pcache_segment_info *seg_info; +}; + +int segment_copy_to_bio(struct pcache_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off); +int segment_copy_from_bio(struct pcache_segment *segment, + u32 data_off, u32 data_len, struct bio *bio, u32 bio_off); + +static inline void segment_pos_advance(struct pcache_segment_pos *seg_pos, u32 len) +{ + BUG_ON(seg_pos->off + len > seg_pos->segment->data_size); + + seg_pos->off += len; +} + +void pcache_segment_init(struct pcache_cache_dev *cache_dev, struct pcache_segment *segment, + struct pcache_segment_init_options *options); +#endif /* _PCACHE_SEGMENT_H */ -- cgit v1.3.1