Both exec and exit want to ensure that the uaccess routines actually do access user pointers. Use the newly added force_uaccess_begin helper instead of an open coded set_fs for that to prepare for kernel builds where set_fs() does not exist. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- fs/exec.c | 7 ++++++- kernel/exit.c | 2 +- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index e6e8a9a7032784..769af470b69124 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1380,7 +1380,12 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) goto out_unlock; - set_fs(USER_DS); + /* + * Ensure that the uaccess routines can actually operate on userspace + * pointers: + */ + force_uaccess_begin(); + me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE | PF_NO_SETAFFINITY); flush_thread(); diff --git a/kernel/exit.c b/kernel/exit.c index 727150f2810338..17d486a20f0dc6 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -731,7 +731,7 @@ void __noreturn do_exit(long code) * mm_release()->clear_child_tid() from writing to a user-controlled * kernel address. */ - set_fs(USER_DS); + force_uaccess_begin(); if (unlikely(in_atomic())) { pr_info("note: %s[%d] exited with preempt_count %d\n", -- 2.26.2