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authorLino Sanfilippo <LinoSanfilippo@gmx.de>2010-11-09 18:18:16 +0100
committerEric Paris <eparis@redhat.com>2010-12-07 16:14:21 -0500
commitfa218ab98c31eeacd12b89501e6b99d146ea56cc (patch)
tree789e0f922fbb30844a89a4aaf707c01991c74ea3 /fs/notify/fanotify/fanotify_user.c
parentb1085ba80cd2784400a7beec3fda5099198ed01c (diff)
fanotify: correct broken ref counting in case adding a mark failed
If adding a mount or inode mark failed fanotify_free_mark() is called explicitly. But at this time the mark has already been put into the destroy list of the fsnotify_mark kernel thread. If the thread is too slow it will try to decrease the reference of a mark, that has already been freed by fanotify_free_mark(). (If its fast enough it will only decrease the marks ref counter from 2 to 1 - note that the counter has been increased to 2 in add_mark() - which has practically no effect.) This patch fixes the ref counting by not calling free_mark() explicitly, but decreasing the ref counter and rely on the fsnotify_mark thread to cleanup in case adding the mark has failed. Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de> Signed-off-by: Eric Paris <eparis@redhat.com>
Diffstat (limited to 'fs/notify/fanotify/fanotify_user.c')
-rw-r--r--fs/notify/fanotify/fanotify_user.c31
1 files changed, 14 insertions, 17 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 045c0794d43..c0ca1fa1550 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -594,11 +594,10 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
{
struct fsnotify_mark *fsn_mark;
__u32 added;
+ int ret = 0;
fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
if (!fsn_mark) {
- int ret;
-
if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
return -ENOSPC;
@@ -608,17 +607,16 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
fsnotify_init_mark(fsn_mark, fanotify_free_mark);
ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
- if (ret) {
- fanotify_free_mark(fsn_mark);
- return ret;
- }
+ if (ret)
+ goto err;
}
added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
- fsnotify_put_mark(fsn_mark);
+
if (added & ~mnt->mnt_fsnotify_mask)
fsnotify_recalc_vfsmount_mask(mnt);
-
- return 0;
+err:
+ fsnotify_put_mark(fsn_mark);
+ return ret;
}
static int fanotify_add_inode_mark(struct fsnotify_group *group,
@@ -627,6 +625,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
{
struct fsnotify_mark *fsn_mark;
__u32 added;
+ int ret = 0;
pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
@@ -642,8 +641,6 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
fsn_mark = fsnotify_find_inode_mark(group, inode);
if (!fsn_mark) {
- int ret;
-
if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
return -ENOSPC;
@@ -653,16 +650,16 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
fsnotify_init_mark(fsn_mark, fanotify_free_mark);
ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
- if (ret) {
- fanotify_free_mark(fsn_mark);
- return ret;
- }
+ if (ret)
+ goto err;
}
added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
- fsnotify_put_mark(fsn_mark);
+
if (added & ~inode->i_fsnotify_mask)
fsnotify_recalc_inode_mask(inode);
- return 0;
+err:
+ fsnotify_put_mark(fsn_mark);
+ return ret;
}
/* fanotify syscalls */