Commit 580c57f1 authored Feb 17, 2015 by Kees Cook Committed by Linus Torvalds Feb 17, 2015

seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO



The value resulting from the SECCOMP_RET_DATA mask could exceed MAX_ERRNO
when setting errno during a SECCOMP_RET_ERRNO filter action.  This makes
sure we have a reliable value being set, so that an invalid errno will not
be ignored by userspace.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3a9af0bd

kernel/seccomp.c

+3 −1

Original line number	Original line	Diff line number	Diff line
	@@ -629,7 +629,9 @@ static u32 __seccomp_phase1_filter(int this_syscall, struct seccomp_data *sd)

	switch (action) {		switch (action) {
	case SECCOMP_RET_ERRNO:		case SECCOMP_RET_ERRNO:
	/* Set the low-order 16-bits as a errno. */		/* Set low-order bits as an errno, capped at MAX_ERRNO. */
			if (data > MAX_ERRNO)
			data = MAX_ERRNO;
	syscall_set_return_value(current, task_pt_regs(current),		syscall_set_return_value(current, task_pt_regs(current),
	-data, 0);		-data, 0);
	goto skip;		goto skip;