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![Gabriel Krisman Bertazi](/assets/img/avatar_default.png)
Commit2991552447
("entry: Drop usage of TIF flags in the generic syscall code") introduced a bug on architectures using the generic syscall entry code, in which processes stopped by PTRACE_SYSCALL do not trap on syscall return after receiving a TIF_SINGLESTEP. The reason is that the meaning of TIF_SINGLESTEP flag is overloaded to cause the trap after a system call is executed, but since the above commit, the syscall call handler only checks for the SYSCALL_WORK flags on the exit work. Split the meaning of TIF_SINGLESTEP such that it only means single-step mode, and create a new type of SYSCALL_WORK to request a trap immediately after a syscall in single-step mode. In the current implementation, the SYSCALL_WORK flag shadows the TIF_SINGLESTEP flag for simplicity. Update x86 to flip this bit when a tracer enables single stepping. Fixes:2991552447
("entry: Drop usage of TIF flags in the generic syscall code") Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Kyle Huey <me@kylehuey.com> Link: https://lore.kernel.org/r/87h7mtc9pr.fsf_-_@collabora.com
214 lines
6.2 KiB
C
214 lines
6.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* thread_info.h: common low-level thread information accessors
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* - Incorporating suggestions made by Linus Torvalds
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*/
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#ifndef _LINUX_THREAD_INFO_H
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#define _LINUX_THREAD_INFO_H
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#include <linux/types.h>
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#include <linux/bug.h>
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#include <linux/restart_block.h>
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#ifdef CONFIG_THREAD_INFO_IN_TASK
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/*
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* For CONFIG_THREAD_INFO_IN_TASK kernels we need <asm/current.h> for the
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* definition of current, but for !CONFIG_THREAD_INFO_IN_TASK kernels,
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* including <asm/current.h> can cause a circular dependency on some platforms.
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*/
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#include <asm/current.h>
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#define current_thread_info() ((struct thread_info *)current)
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#endif
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#include <linux/bitops.h>
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/*
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* For per-arch arch_within_stack_frames() implementations, defined in
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* asm/thread_info.h.
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*/
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enum {
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BAD_STACK = -1,
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NOT_STACK = 0,
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GOOD_FRAME,
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GOOD_STACK,
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};
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#ifdef CONFIG_GENERIC_ENTRY
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enum syscall_work_bit {
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SYSCALL_WORK_BIT_SECCOMP,
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SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
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SYSCALL_WORK_BIT_SYSCALL_TRACE,
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SYSCALL_WORK_BIT_SYSCALL_EMU,
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SYSCALL_WORK_BIT_SYSCALL_AUDIT,
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SYSCALL_WORK_BIT_SYSCALL_USER_DISPATCH,
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SYSCALL_WORK_BIT_SYSCALL_EXIT_TRAP,
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};
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#define SYSCALL_WORK_SECCOMP BIT(SYSCALL_WORK_BIT_SECCOMP)
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#define SYSCALL_WORK_SYSCALL_TRACEPOINT BIT(SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT)
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#define SYSCALL_WORK_SYSCALL_TRACE BIT(SYSCALL_WORK_BIT_SYSCALL_TRACE)
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#define SYSCALL_WORK_SYSCALL_EMU BIT(SYSCALL_WORK_BIT_SYSCALL_EMU)
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#define SYSCALL_WORK_SYSCALL_AUDIT BIT(SYSCALL_WORK_BIT_SYSCALL_AUDIT)
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#define SYSCALL_WORK_SYSCALL_USER_DISPATCH BIT(SYSCALL_WORK_BIT_SYSCALL_USER_DISPATCH)
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#define SYSCALL_WORK_SYSCALL_EXIT_TRAP BIT(SYSCALL_WORK_BIT_SYSCALL_EXIT_TRAP)
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#endif
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#include <asm/thread_info.h>
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#ifdef __KERNEL__
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#ifndef THREAD_ALIGN
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#define THREAD_ALIGN THREAD_SIZE
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#endif
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#define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO)
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/*
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* flag set/clear/test wrappers
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* - pass TIF_xxxx constants to these functions
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*/
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static inline void set_ti_thread_flag(struct thread_info *ti, int flag)
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{
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set_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline void clear_ti_thread_flag(struct thread_info *ti, int flag)
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{
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clear_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline void update_ti_thread_flag(struct thread_info *ti, int flag,
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bool value)
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{
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if (value)
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set_ti_thread_flag(ti, flag);
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else
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clear_ti_thread_flag(ti, flag);
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}
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static inline int test_and_set_ti_thread_flag(struct thread_info *ti, int flag)
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{
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return test_and_set_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline int test_and_clear_ti_thread_flag(struct thread_info *ti, int flag)
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{
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return test_and_clear_bit(flag, (unsigned long *)&ti->flags);
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}
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static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
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{
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return test_bit(flag, (unsigned long *)&ti->flags);
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}
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#define set_thread_flag(flag) \
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set_ti_thread_flag(current_thread_info(), flag)
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#define clear_thread_flag(flag) \
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clear_ti_thread_flag(current_thread_info(), flag)
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#define update_thread_flag(flag, value) \
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update_ti_thread_flag(current_thread_info(), flag, value)
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#define test_and_set_thread_flag(flag) \
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test_and_set_ti_thread_flag(current_thread_info(), flag)
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#define test_and_clear_thread_flag(flag) \
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test_and_clear_ti_thread_flag(current_thread_info(), flag)
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#define test_thread_flag(flag) \
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test_ti_thread_flag(current_thread_info(), flag)
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#ifdef CONFIG_GENERIC_ENTRY
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#define set_syscall_work(fl) \
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set_bit(SYSCALL_WORK_BIT_##fl, ¤t_thread_info()->syscall_work)
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#define test_syscall_work(fl) \
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test_bit(SYSCALL_WORK_BIT_##fl, ¤t_thread_info()->syscall_work)
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#define clear_syscall_work(fl) \
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clear_bit(SYSCALL_WORK_BIT_##fl, ¤t_thread_info()->syscall_work)
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#define set_task_syscall_work(t, fl) \
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set_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
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#define test_task_syscall_work(t, fl) \
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test_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
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#define clear_task_syscall_work(t, fl) \
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clear_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
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#else /* CONFIG_GENERIC_ENTRY */
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#define set_syscall_work(fl) \
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set_ti_thread_flag(current_thread_info(), TIF_##fl)
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#define test_syscall_work(fl) \
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test_ti_thread_flag(current_thread_info(), TIF_##fl)
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#define clear_syscall_work(fl) \
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clear_ti_thread_flag(current_thread_info(), TIF_##fl)
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#define set_task_syscall_work(t, fl) \
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set_ti_thread_flag(task_thread_info(t), TIF_##fl)
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#define test_task_syscall_work(t, fl) \
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test_ti_thread_flag(task_thread_info(t), TIF_##fl)
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#define clear_task_syscall_work(t, fl) \
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clear_ti_thread_flag(task_thread_info(t), TIF_##fl)
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#endif /* !CONFIG_GENERIC_ENTRY */
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#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED)
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#ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES
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static inline int arch_within_stack_frames(const void * const stack,
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const void * const stackend,
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const void *obj, unsigned long len)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_HARDENED_USERCOPY
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extern void __check_object_size(const void *ptr, unsigned long n,
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bool to_user);
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static __always_inline void check_object_size(const void *ptr, unsigned long n,
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bool to_user)
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{
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if (!__builtin_constant_p(n))
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__check_object_size(ptr, n, to_user);
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}
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#else
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static inline void check_object_size(const void *ptr, unsigned long n,
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bool to_user)
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{ }
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#endif /* CONFIG_HARDENED_USERCOPY */
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extern void __compiletime_error("copy source size is too small")
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__bad_copy_from(void);
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extern void __compiletime_error("copy destination size is too small")
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__bad_copy_to(void);
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static inline void copy_overflow(int size, unsigned long count)
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{
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WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
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}
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static __always_inline __must_check bool
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check_copy_size(const void *addr, size_t bytes, bool is_source)
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{
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int sz = __compiletime_object_size(addr);
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if (unlikely(sz >= 0 && sz < bytes)) {
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if (!__builtin_constant_p(bytes))
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copy_overflow(sz, bytes);
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else if (is_source)
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__bad_copy_from();
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else
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__bad_copy_to();
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return false;
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}
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if (WARN_ON_ONCE(bytes > INT_MAX))
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return false;
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check_object_size(addr, bytes, is_source);
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return true;
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}
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#ifndef arch_setup_new_exec
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static inline void arch_setup_new_exec(void) { }
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#endif
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#endif /* __KERNEL__ */
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#endif /* _LINUX_THREAD_INFO_H */
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