Commit fe814175 authored Aug 11, 2020 by Christoph Hellwig Committed by Linus Torvalds Aug 12, 2020

exec: use force_uaccess_begin during exec and exit



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@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Link: http://lkml.kernel.org/r/20200710135706.537715-7-hch@lst.de


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3d13f313

fs/exec.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -1402,7 +1402,12 @@ 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();

kernel/exit.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -732,7 +732,7 @@ 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",