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 --- net/xdp/xsk_queue.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 net/xdp/xsk_queue.c (limited to 'net/xdp/xsk_queue.c') diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c new file mode 100644 index 000000000..4dd01b7d8 --- /dev/null +++ b/net/xdp/xsk_queue.c @@ -0,0 +1,66 @@ +// SPDX-License-Identifier: GPL-2.0 +/* XDP user-space ring structure + * Copyright(c) 2018 Intel Corporation. + */ + +#include +#include +#include +#include +#include + +#include "xsk_queue.h" + +static size_t xskq_get_ring_size(struct xsk_queue *q, bool umem_queue) +{ + struct xdp_umem_ring *umem_ring; + struct xdp_rxtx_ring *rxtx_ring; + + if (umem_queue) + return struct_size(umem_ring, desc, q->nentries); + return struct_size(rxtx_ring, desc, q->nentries); +} + +struct xsk_queue *xskq_create(u32 nentries, bool umem_queue) +{ + struct xsk_queue *q; + size_t size; + + q = kzalloc_obj(*q); + if (!q) + return NULL; + + q->nentries = nentries; + q->ring_mask = nentries - 1; + + size = xskq_get_ring_size(q, umem_queue); + + /* size which is overflowing or close to SIZE_MAX will become 0 in + * PAGE_ALIGN(), checking SIZE_MAX is enough due to the previous + * is_power_of_2(), the rest will be handled by vmalloc_user() + */ + if (unlikely(size == SIZE_MAX)) { + kfree(q); + return NULL; + } + + size = PAGE_ALIGN(size); + + q->ring = vmalloc_user(size); + if (!q->ring) { + kfree(q); + return NULL; + } + + q->ring_vmalloc_size = size; + return q; +} + +void xskq_destroy(struct xsk_queue *q) +{ + if (!q) + return; + + vfree(q->ring); + kfree(q); +} -- cgit v1.3.1