| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.1 62/86] ovl: fix dentry reference leak | Date | Fri, 6 Nov 2015 11:23:01 -0800 |
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4.1-stable review patch. If anyone has any objections, please let me know.
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From: David Howells <dhowells@redhat.com>
commit ab79efab0a0ba01a74df782eb7fa44b044dae8b5 upstream.
In ovl_copy_up_locked(), newdentry is leaked if the function exits through out_cleanup as this just to out after calling ovl_cleanup() - which doesn't actually release the ref on newdentry.
The out_cleanup segment should instead exit through out2 as certainly newdentry leaks - and possibly upper does also, though this isn't caught given the catch of newdentry.
Without this fix, something like the following is seen:
BUG: Dentry ffff880023e9eb20{i=f861,n=#ffff880023e82d90} still in use (1) [unmount of tmpfs tmpfs] BUG: Dentry ffff880023ece640{i=0,n=bigfile} still in use (1) [unmount of tmpfs tmpfs]
when unmounting the upper layer after an error occurred in copyup.
An error can be induced by creating a big file in a lower layer with something like:
dd if=/dev/zero of=/lower/a/bigfile bs=65536 count=1 seek=$((0xf000))
to create a large file (4.1G). Overlay an upper layer that is too small (on tmpfs might do) and then induce a copy up by opening it writably.
Reported-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/overlayfs/copy_up.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -267,7 +267,7 @@ out: out_cleanup: ovl_cleanup(wdir, newdentry); - goto out; + goto out2; } /*
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