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 --- fs/nfsd/cache.h | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 fs/nfsd/cache.h (limited to 'fs/nfsd/cache.h') diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h new file mode 100644 index 000000000..bb7addef4 --- /dev/null +++ b/fs/nfsd/cache.h @@ -0,0 +1,91 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Request reply cache. This was heavily inspired by the + * implementation in 4.3BSD/4.4BSD. + * + * Copyright (C) 1995, 1996 Olaf Kirch + */ + +#ifndef NFSCACHE_H +#define NFSCACHE_H + +#include +#include "nfsd.h" + +/* + * Representation of a reply cache entry. + * + * Note that we use a sockaddr_in6 to hold the address instead of the more + * typical sockaddr_storage. This is for space reasons, since sockaddr_storage + * is much larger than a sockaddr_in6. + */ +struct nfsd_cacherep { + struct { + /* Keep often-read xid, csum in the same cache line: */ + __be32 k_xid; + __wsum k_csum; + u32 k_proc; + u32 k_prot; + u32 k_vers; + unsigned int k_len; + struct sockaddr_in6 k_addr; + } c_key; + + struct rb_node c_node; + struct list_head c_lru; + unsigned char c_state, /* unused, inprog, done */ + c_type, /* status, buffer */ + c_secure : 1; /* req came from port < 1024 */ + unsigned long c_timestamp; + union { + struct kvec u_vec; + __be32 u_status; + } c_u; +}; + +#define c_replvec c_u.u_vec +#define c_replstat c_u.u_status + +/* cache entry states */ +enum { + RC_UNUSED, + RC_INPROG, + RC_DONE +}; + +/* return values */ +enum { + RC_DROPIT, + RC_REPLY, + RC_DOIT +}; + +/* + * Cache types. + * We may want to add more types one day, e.g. for diropres and + * attrstat replies. Using cache entries with fixed length instead + * of buffer pointers may be more efficient. + */ +enum { + RC_NOCACHE, + RC_REPLSTAT, + RC_REPLBUFF, +}; + +/* Cache entries expire after this time period */ +#define RC_EXPIRE (120 * HZ) + +/* Checksum this amount of the request */ +#define RC_CSUMLEN (256U) + +int nfsd_drc_slab_create(void); +void nfsd_drc_slab_free(void); +int nfsd_reply_cache_init(struct nfsd_net *); +void nfsd_reply_cache_shutdown(struct nfsd_net *); +int nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start, + unsigned int len, struct nfsd_cacherep **cacherep); +void nfsd_cache_update(struct svc_rqst *rqstp, struct nfsd_cacherep *rp, + int cachetype, __be32 *statp); +int nfsd_reply_cache_stats_show(struct seq_file *m, void *v); + +#endif /* NFSCACHE_H */ -- cgit v1.3.1