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 | 2 +- include/linux/sched.h | 2 +- include/uapi/linux/futex.h | 10 ++++++++++ kernel/futex/core.c | 20 ++++++++++---------- kernel/futex/syscalls.c | 8 ++++---- 6 files changed, 29 insertions(+), 26 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 56cebaff0c91..2c5a7f980182 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -385,15 +385,8 @@ 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 { @@ -672,7 +665,7 @@ 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 9e9750f04980..322851e4a703 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -66,7 +66,7 @@ static inline void futex_init_task(struct task_struct *tsk) { tsk->robust_list = NULL; #ifdef CONFIG_COMPAT - tsk->compat_robust_list = NULL; + tsk->robust_list32 = NULL; #endif INIT_LIST_HEAD(&tsk->pi_state_list); tsk->pi_state_cache = NULL; diff --git a/include/linux/sched.h b/include/linux/sched.h index cbb7340c5866..76cabfab5b73 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1332,7 +1332,7 @@ struct task_struct { #ifdef CONFIG_FUTEX 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/uapi/linux/futex.h b/include/uapi/linux/futex.h index 7e2744ec8933..86efb089893d 100644 --- a/include/uapi/linux/futex.h +++ b/include/uapi/linux/futex.h @@ -153,6 +153,16 @@ 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 125804fbb5cb..c99d7baab24e 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -1227,7 +1227,7 @@ 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, +fetch_robust_entry32(compat_uptr_t *uentry, struct robust_list __user **entry, compat_uptr_t __user *head, unsigned int *pi) { if (get_user(*uentry, head)) @@ -1245,9 +1245,9 @@ 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 = curr->compat_robust_list; + struct robust_list_head32 __user *head = curr->robust_list32; struct robust_list __user *entry, *next_entry, *pending; unsigned int limit = ROBUST_LIST_LIMIT, pi, pip; unsigned int next_pi; @@ -1259,7 +1259,7 @@ 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, &pi)) + if (fetch_robust_entry32(&uentry, &entry, &head->list.next, &pi)) return; /* * Fetch the relative futex offset: @@ -1270,7 +1270,7 @@ 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, + if (fetch_robust_entry32(&upending, &pending, &head->list_op_pending, &pip)) return; @@ -1280,8 +1280,8 @@ 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, - (compat_uptr_t __user *)&entry->next, &next_pi); + rc = fetch_robust_entry32(&next_uentry, &next_entry, + (u32 __user *)&entry->next, &next_pi); /* * A pending lock might already be on the list, so * dont process it twice: @@ -1413,9 +1413,9 @@ static void futex_cleanup(struct task_struct *tsk) } #ifdef CONFIG_COMPAT - if (unlikely(tsk->compat_robust_list)) { - compat_exit_robust_list(tsk); - tsk->compat_robust_list = NULL; + if (unlikely(tsk->robust_list32)) { + exit_robust_list32(tsk); + tsk->robust_list32 = NULL; } #endif diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 880c9bf2f315..1de8ff230d54 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -43,7 +43,7 @@ static inline void __user *futex_task_robust_list(struct task_struct *p, bool co { #ifdef CONFIG_COMPAT if (compat) - return p->compat_robust_list; + return p->robust_list32; #endif return p->robust_list; } @@ -468,13 +468,13 @@ SYSCALL_DEFINE4(futex_requeue, #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE2(set_robust_list, - struct compat_robust_list_head __user *, head, + struct robust_list_head32 __user *, head, compat_size_t, len) { if (unlikely(len != sizeof(*head))) return -EINVAL; - current->compat_robust_list = head; + current->robust_list32 = head; return 0; } @@ -483,7 +483,7 @@ 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); -- 2.52.0
