From e6485a47b758cae04a496764a1095961ee3249e4 Mon Sep 17 00:00:00 2001
From: Andrea Arcangeli <aarcange@redhat.com>
Date: Fri, 4 Sep 2015 15:47:15 -0700
Subject: [PATCH] userfaultfd: require UFFDIO_API before other ioctls
UFFDIO_API was already forced before read/poll could work. This makes the
code more strict to force it also for all other ioctls.
All users would already have been required to call UFFDIO_API before
invoking other ioctls but this makes it more explicit.
This will ensure we can change all ioctls (all but UFFDIO_API/struct
uffdio_api) with a bump of uffdio_api.api.
There's no actual plan or need to change the API or the ioctl, the current
API already should cover fine even the non cooperative usage, but this is
just for the longer term future just in case.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/userfaultfd.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 5f11678907d5..af88ef6fffff 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -577,7 +577,6 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf,
if (ctx->state == UFFD_STATE_WAIT_API)
return -EINVAL;
- BUG_ON(ctx->state != UFFD_STATE_RUNNING);
for (;;) {
if (count < sizeof(msg))
@@ -1115,6 +1114,9 @@ static long userfaultfd_ioctl(struct file *file, unsigned cmd,
int ret = -EINVAL;
struct userfaultfd_ctx *ctx = file->private_data;
+ if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API)
+ return -EINVAL;
+
switch(cmd) {
case UFFDIO_API:
ret = userfaultfd_api(ctx, arg);
--
2.34.1