| Message ID | 20200629144145.GA3183@techsingularity.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Revert "fs: Do not check if there is a fsnotify watcher on pseudo inodes" | expand |
On Mon 29-06-20 15:41:45, Mel Gorman wrote: > This reverts commit e9c15badbb7b ("fs: Do not check if there is a > fsnotify watcher on pseudo inodes"). The commit intended to eliminate > fsnotify-related overhead for pseudo inodes but it is broken in > concept. inotify can receive events of pipe files under /proc/X/fd and > chromium relies on close and open events for sandboxing. Maxim Levitsky > reported the following > > Chromium starts as a white rectangle, shows few white rectangles that > resemble its notifications and then crashes. > > The stdout output from chromium: > > [mlevitsk@starship ~]$chromium-freeworld > mesa: for the --simplifycfg-sink-common option: may only occur zero or one times! > mesa: for the --global-isel-abort option: may only occur zero or one times! > [3379:3379:0628/135151.440930:ERROR:browser_switcher_service.cc(238)] XXX Init() > ../../sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc:**CRASHING**:seccomp-bpf failure in syscall 0072 > Received signal 11 SEGV_MAPERR 0000004a9048 > > Crashes are not universal but even if chromium does not crash, it certainly > does not work properly. While filtering just modify and access might be > safe, the benefit is not worth the risk hence the revert. > > Reported-by: Maxim Levitsky <mlevitsk@redhat.com> > Fixes: e9c15badbb7b ("fs: Do not check if there is a fsnotify watcher on pseudo inodes") > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Thanks for the revert Mel. I can see Linus already picked it up so we are done. Honza > --- > fs/file_table.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/file_table.c b/fs/file_table.c > index 65603502fed6..656647f9575a 100644 > --- a/fs/file_table.c > +++ b/fs/file_table.c > @@ -230,7 +230,7 @@ struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt, > d_set_d_op(path.dentry, &anon_ops); > path.mnt = mntget(mnt); > d_instantiate(path.dentry, inode); > - file = alloc_file(&path, flags | FMODE_NONOTIFY, fops); > + file = alloc_file(&path, flags, fops); > if (IS_ERR(file)) { > ihold(inode); > path_put(&path);
diff --git a/fs/file_table.c b/fs/file_table.c index 65603502fed6..656647f9575a 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -230,7 +230,7 @@ struct file *alloc_file_pseudo(struct inode *inode, struct vfsmount *mnt, d_set_d_op(path.dentry, &anon_ops); path.mnt = mntget(mnt); d_instantiate(path.dentry, inode); - file = alloc_file(&path, flags | FMODE_NONOTIFY, fops); + file = alloc_file(&path, flags, fops); if (IS_ERR(file)) { ihold(inode); path_put(&path);
This reverts commit e9c15badbb7b ("fs: Do not check if there is a fsnotify watcher on pseudo inodes"). The commit intended to eliminate fsnotify-related overhead for pseudo inodes but it is broken in concept. inotify can receive events of pipe files under /proc/X/fd and chromium relies on close and open events for sandboxing. Maxim Levitsky reported the following Chromium starts as a white rectangle, shows few white rectangles that resemble its notifications and then crashes. The stdout output from chromium: [mlevitsk@starship ~]$chromium-freeworld mesa: for the --simplifycfg-sink-common option: may only occur zero or one times! mesa: for the --global-isel-abort option: may only occur zero or one times! [3379:3379:0628/135151.440930:ERROR:browser_switcher_service.cc(238)] XXX Init() ../../sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc:**CRASHING**:seccomp-bpf failure in syscall 0072 Received signal 11 SEGV_MAPERR 0000004a9048 Crashes are not universal but even if chromium does not crash, it certainly does not work properly. While filtering just modify and access might be safe, the benefit is not worth the risk hence the revert. Reported-by: Maxim Levitsky <mlevitsk@redhat.com> Fixes: e9c15badbb7b ("fs: Do not check if there is a fsnotify watcher on pseudo inodes") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- fs/file_table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)