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 --- tools/perf/util/rwsem.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 tools/perf/util/rwsem.h (limited to 'tools/perf/util/rwsem.h') diff --git a/tools/perf/util/rwsem.h b/tools/perf/util/rwsem.h new file mode 100644 index 000000000..b102d8143 --- /dev/null +++ b/tools/perf/util/rwsem.h @@ -0,0 +1,30 @@ +#ifndef _PERF_RWSEM_H +#define _PERF_RWSEM_H + +#include +#include "mutex.h" + +/* + * Mutexes have additional error checking. Enable to use a mutex rather than a + * rwlock for debugging. + */ +#define RWS_ERRORCHECK 0 + +struct LOCKABLE rw_semaphore { +#if RWS_ERRORCHECK + struct mutex mtx; +#else + pthread_rwlock_t lock; +#endif +}; + +int init_rwsem(struct rw_semaphore *sem); +int exit_rwsem(struct rw_semaphore *sem); + +int down_read(struct rw_semaphore *sem) SHARED_LOCK_FUNCTION(sem); +int up_read(struct rw_semaphore *sem) UNLOCK_FUNCTION(sem); + +int down_write(struct rw_semaphore *sem) EXCLUSIVE_LOCK_FUNCTION(sem); +int up_write(struct rw_semaphore *sem) UNLOCK_FUNCTION(sem); + +#endif /* _PERF_RWSEM_H */ -- cgit v1.3.1