Subject: [merged] inotify-fix-race-when-adding-a-new-watch.patch removed from -mm tree To: LinoSanfilippo@xxxxxx,eparis@xxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Tue, 09 Jul 2013 16:19:16 -0700 The patch titled Subject: inotify: fix race when adding a new watch has been removed from the -mm tree. Its filename was inotify-fix-race-when-adding-a-new-watch.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Lino Sanfilippo <LinoSanfilippo@xxxxxx> Subject: inotify: fix race when adding a new watch In inotify_new_watch() the number of watches for a group is compared against the max number of allowed watches and increased afterwards. The check and incrementation is not done atomically, so it is possible for multiple concurrent threads to pass the check and increment the number of marks above the allowed max. This patch uses an inotify groups mark_lock to ensure that both check and incrementation are done atomic. Furthermore we dont have to worry about the race that allows a concurrent thread to add a watch just after inotify_update_existing_watch() returned with -ENOENT anymore, since this is also synchronized by the groups mark mutex now. Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx> Cc: Eric Paris <eparis@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/notify/inotify/inotify_user.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff -puN fs/notify/inotify/inotify_user.c~inotify-fix-race-when-adding-a-new-watch fs/notify/inotify/inotify_user.c --- a/fs/notify/inotify/inotify_user.c~inotify-fix-race-when-adding-a-new-watch +++ a/fs/notify/inotify/inotify_user.c @@ -636,7 +636,8 @@ static int inotify_new_watch(struct fsno goto out_err; /* we are on the idr, now get on the inode */ - ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0); + ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, group, inode, + NULL, 0); if (ret) { /* we failed to get on the inode, get off the idr */ inotify_remove_from_idr(group, tmp_i_mark); @@ -660,19 +661,13 @@ static int inotify_update_watch(struct f { int ret = 0; -retry: + mutex_lock(&group->mark_mutex); /* try to update and existing watch with the new arg */ ret = inotify_update_existing_watch(group, inode, arg); /* no mark present, try to add a new one */ if (ret == -ENOENT) ret = inotify_new_watch(group, inode, arg); - /* - * inotify_new_watch could race with another thread which did an - * inotify_new_watch between the update_existing and the add watch - * here, go back and try to update an existing mark again. - */ - if (ret == -EEXIST) - goto retry; + mutex_unlock(&group->mark_mutex); return ret; } _ Patches currently in -mm which might be from LinoSanfilippo@xxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html