tree 3fc1fe1e0f40d673d9675a3db5b84ca00b81eaea
parent 7544953685859875b5ac0260b6b1856066c092d6
author John McCutchan <[EMAIL PROTECTED]> Mon, 01 Aug 2005 19:00:45 -0400
committer Linus Torvalds <[EMAIL PROTECTED]> Mon, 01 Aug 2005 23:16:53 -0700
[PATCH] inotify: fix race between the kernel and user space
When you rm a watch, an IN_IGNORED event is sent down the event queue
with the watch descriptor that you just rm'd.
If you then add a watch you could get the ignored watch's wd and if you
haven't read the entire event queue, user space will think that it's
newly created watch was just ignored.
To avoid this problem we just use idr_get_new_above instead of
idr_get_new.
Signed-off-by: John McCutchan <[EMAIL PROTECTED]>
Signed-off-by: Robert Love <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
fs/inotify.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/inotify.c b/fs/inotify.c
--- a/fs/inotify.c
+++ b/fs/inotify.c
@@ -90,6 +90,7 @@ struct inotify_device {
unsigned int queue_size; /* size of the queue (bytes) */
unsigned int event_count; /* number of pending events */
unsigned int max_events; /* maximum number of events */
+ u32 last_wd; /* the last wd allocated */
};
/*
@@ -352,7 +353,7 @@ static int inotify_dev_get_wd(struct ino
do {
if (unlikely(!idr_pre_get(&dev->idr, GFP_KERNEL)))
return -ENOSPC;
- ret = idr_get_new(&dev->idr, watch, &watch->wd);
+ ret = idr_get_new_above(&dev->idr, watch, dev->last_wd,
&watch->wd);
} while (ret == -EAGAIN);
return ret;
@@ -401,6 +402,7 @@ static struct inotify_watch *create_watc
return ERR_PTR(ret);
}
+ dev->last_wd = ret;
watch->mask = mask;
atomic_set(&watch->count, 0);
INIT_LIST_HEAD(&watch->d_list);
@@ -899,6 +901,7 @@ asmlinkage long sys_inotify_init(void)
dev->queue_size = 0;
dev->max_events = inotify_max_queued_events;
dev->user = user;
+ dev->last_wd = 0;
atomic_set(&dev->count, 0);
get_inotify_dev(dev);
-
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