There are two functions for handling robust lists during a task exit: exit_robust_list() and compat_exit_robust_list(). The first one handles either 64-bit or 32-bit lists, depending on the kernel bitness. compat_exit_robust_list() exists only in 64-bit kernels that supports 32-bit syscalls entry points (also known as compat entry points).
The new syscall set_robust_list2() needs to handle both 64-bit and 32-bit robust lists, regardless of compat entry being enabled, so it needs to have both functions always available. In preparation for this, use explicit size for struct members of compat_robust_list and compat_robust_list_head. Rename the structs and compat_exit_robust_list() to make clear which bitness it handles. Keep exit_robust_list() as it is: used to handle the native bit size of the kernel. Signed-off-by: André Almeida <[email protected]> --- include/linux/compat.h | 13 +++---------- include/linux/futex.h | 4 ++++ include/linux/futex_types.h | 2 +- include/linux/sched.h | 2 -- include/uapi/linux/futex.h | 10 ++++++++++ kernel/futex/core.c | 34 +++++++++++++++++----------------- kernel/futex/syscalls.c | 9 +++++---- 7 files changed, 40 insertions(+), 34 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 8da0a15c95f4..eceb085efb69 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -389,15 +389,8 @@ struct compat_ifconf { compat_caddr_t ifcbuf; }; -struct compat_robust_list { - compat_uptr_t next; -}; - -struct compat_robust_list_head { - struct compat_robust_list list; - compat_long_t futex_offset; - compat_uptr_t list_op_pending; -}; +struct robust_list32; +struct robust_list_head32; #ifdef CONFIG_COMPAT_OLD_SIGACTION struct compat_old_sigaction { @@ -676,7 +669,7 @@ asmlinkage long compat_sys_waitid(int, compat_pid_t, struct compat_siginfo __user *, int, struct compat_rusage __user *); asmlinkage long -compat_sys_set_robust_list(struct compat_robust_list_head __user *head, +compat_sys_set_robust_list(struct robust_list_head32 __user *head, compat_size_t len); asmlinkage long compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, diff --git a/include/linux/futex.h b/include/linux/futex.h index 18ed18d5cbc1..1d1a8a627a8b 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -68,6 +68,10 @@ static inline void futex_init_task(struct task_struct *tsk) INIT_LIST_HEAD(&tsk->futex.pi_state_list); tsk->futex.state = FUTEX_STATE_OK; mutex_init(&tsk->futex.exit_mutex); + tsk->futex.robust_list = NULL; +#ifdef CONFIG_COMPAT + tsk->futex.robust_list32 = NULL; +#endif } void futex_exit_recursive(struct task_struct *tsk); diff --git a/include/linux/futex_types.h b/include/linux/futex_types.h index d320c0571f0c..2c9ad20f3be8 100644 --- a/include/linux/futex_types.h +++ b/include/linux/futex_types.h @@ -23,7 +23,7 @@ struct robust_list_head; struct futex_sched_data { struct robust_list_head __user *robust_list; #ifdef CONFIG_COMPAT - struct compat_robust_list_head __user *compat_robust_list; + struct robust_list_head32 __user *robust_list32; #endif struct list_head pi_state_list; struct futex_pi_state *pi_state_cache; diff --git a/include/linux/sched.h b/include/linux/sched.h index 705970d07614..317e55884120 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1360,9 +1360,7 @@ struct task_struct { u32 closid; u32 rmid; #endif - struct futex_sched_data futex; - #ifdef CONFIG_PERF_EVENTS u8 perf_recursion[PERF_NR_CONTEXTS]; struct perf_event_context *perf_event_ctxp; diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h index 10a36c551675..b39f8a23a84b 100644 --- a/include/uapi/linux/futex.h +++ b/include/uapi/linux/futex.h @@ -179,6 +179,16 @@ struct robust_list_head { struct robust_list __user *list_op_pending; }; +struct robust_list32 { + __u32 next; +}; + +struct robust_list_head32 { + struct robust_list32 list; + __s32 futex_offset; + __u32 list_op_pending; +}; + /* * Are there any waiters for this robust futex: */ diff --git a/kernel/futex/core.c b/kernel/futex/core.c index a061f54b606d..4b1bf211c3dc 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -1235,9 +1235,10 @@ static void __user *futex_uaddr(struct robust_list __user *entry, /* * Fetch a robust-list pointer. Bit 0 signals PI futexes: */ -static inline int -compat_fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry, - compat_uptr_t __user *head, unsigned int *pflags) +static inline int fetch_robust_entry32(compat_uptr_t *uentry, + struct robust_list __user **entry, + compat_uptr_t __user *head, + unsigned int *pflags) { if (get_user(*uentry, head)) return -EFAULT; @@ -1254,9 +1255,9 @@ compat_fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **ent * * We silently return on any sign of list-walking problem. */ -static void compat_exit_robust_list(struct task_struct *curr) +static void exit_robust_list32(struct task_struct *curr) { - struct compat_robust_list_head __user *head = current->futex.compat_robust_list; + struct robust_list_head32 __user *head = curr->futex.robust_list32; unsigned int limit = ROBUST_LIST_LIMIT, cur_mod, next_mod, pend_mod; struct robust_list __user *entry, *next_entry, *pending; compat_uptr_t uentry, next_uentry, upending; @@ -1267,7 +1268,7 @@ static void compat_exit_robust_list(struct task_struct *curr) * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): */ - if (compat_fetch_robust_entry(&uentry, &entry, &head->list.next, &cur_mod)) + if (fetch_robust_entry32(&uentry, &entry, &head->list.next, &cur_mod)) return; /* * Fetch the relative futex offset: @@ -1278,7 +1279,7 @@ static void compat_exit_robust_list(struct task_struct *curr) * Fetch any possibly pending lock-add first, and handle it * if it exists: */ - if (compat_fetch_robust_entry(&upending, &pending, &head->list_op_pending, &pend_mod)) + if (fetch_robust_entry32(&upending, &pending, &head->list_op_pending, &pend_mod)) return; next_entry = NULL; /* avoid warning with gcc */ @@ -1287,7 +1288,7 @@ static void compat_exit_robust_list(struct task_struct *curr) * Fetch the next entry in the list before calling * handle_futex_death: */ - rc = compat_fetch_robust_entry(&next_uentry, &next_entry, + rc = fetch_robust_entry32(&next_uentry, &next_entry, (compat_uptr_t __user *)&entry->next, &next_mod); /* * A pending lock might already be on the list, so @@ -1319,20 +1320,20 @@ static void compat_exit_robust_list(struct task_struct *curr) } } -static bool compat_robust_list_clear_pending(u32 __user *pop) +static bool robust_list_clear_pending32(u32 __user *pop) { - struct compat_robust_list_head __user *head = current->futex.compat_robust_list; + struct robust_list_head32 __user *head = current->futex.robust_list32; if (!put_user(0U, pop)) return true; /* See comment in robust_list_clear_pending(). */ if (pop == &head->list_op_pending) - current->futex.compat_robust_list = NULL; + current->futex.robust_list32 = NULL; return false; } #else -static bool compat_robust_list_clear_pending(u32 __user *pop_addr) { return false; } +static bool robust_list_clear_pending32(u32 __user *pop_addr) { return false; } #endif #ifdef CONFIG_FUTEX_PI @@ -1435,7 +1436,7 @@ bool futex_robust_list_clear_pending(void __user *pop, unsigned int flags) return false; if (IS_ENABLED(CONFIG_64BIT) && size32bit) - return compat_robust_list_clear_pending(pop); + return robust_list_clear_pending32(pop); return robust_list_clear_pending(pop); } @@ -1464,12 +1465,11 @@ static void futex_cleanup(struct task_struct *tsk) } #ifdef CONFIG_COMPAT - if (unlikely(tsk->futex.compat_robust_list)) { - compat_exit_robust_list(tsk); - tsk->futex.compat_robust_list = NULL; + if (unlikely(tsk->futex.robust_list32)) { + exit_robust_list32(tsk); + tsk->futex.robust_list32 = NULL; } #endif - if (unlikely(!list_empty(&tsk->futex.pi_state_list))) exit_pi_state_list(tsk); } diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 2fa19d9d008d..4a45bace75fc 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -39,7 +39,7 @@ static inline void __user *futex_task_robust_list(struct task_struct *p, bool co { #ifdef CONFIG_COMPAT if (compat) - return p->futex.compat_robust_list; + return p->futex.robust_list32; #endif return p->futex.robust_list; } @@ -478,13 +478,14 @@ SYSCALL_DEFINE4(futex_requeue, } #ifdef CONFIG_COMPAT -COMPAT_SYSCALL_DEFINE2(set_robust_list, struct compat_robust_list_head __user *, head, +COMPAT_SYSCALL_DEFINE2(set_robust_list, struct robust_list_head32 __user *, head, compat_size_t, len) { if (unlikely(len != sizeof(*head))) return -EINVAL; - current->futex.compat_robust_list = head; + current->futex.robust_list32 = head; + return 0; } @@ -492,7 +493,7 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid, compat_uptr_t __user *, head_ptr, compat_size_t __user *, len_ptr) { - struct compat_robust_list_head __user *head = futex_get_robust_list_common(pid, true); + struct robust_list_head32 __user *head = futex_get_robust_list_common(pid, true); if (IS_ERR(head)) return PTR_ERR(head); -- 2.55.0
