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 --- io_uring/alloc_cache.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 io_uring/alloc_cache.c (limited to 'io_uring/alloc_cache.c') diff --git a/io_uring/alloc_cache.c b/io_uring/alloc_cache.c new file mode 100644 index 000000000..58423888b --- /dev/null +++ b/io_uring/alloc_cache.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "alloc_cache.h" + +void io_alloc_cache_free(struct io_alloc_cache *cache, + void (*free)(const void *)) +{ + void *entry; + + if (!cache->entries) + return; + + while ((entry = io_alloc_cache_get(cache)) != NULL) + free(entry); + + kvfree(cache->entries); + cache->entries = NULL; +} + +/* returns false if the cache was initialized properly */ +bool io_alloc_cache_init(struct io_alloc_cache *cache, + unsigned max_nr, unsigned int size, + unsigned int init_bytes) +{ + cache->entries = kvmalloc_array(max_nr, sizeof(void *), GFP_KERNEL); + if (!cache->entries) + return true; + + cache->nr_cached = 0; + cache->max_cached = max_nr; + cache->elem_size = size; + cache->init_clear = init_bytes; + return false; +} + +void *io_cache_alloc_new(struct io_alloc_cache *cache, gfp_t gfp) +{ + void *obj; + + obj = kmalloc(cache->elem_size, gfp); + if (obj && cache->init_clear) + memset(obj, 0, cache->init_clear); + return obj; +} -- cgit v1.3.1