Messages in this thread Patch in this message | | | Subject | [PATCH 2/2] overlayfs: Fix dentry reference leak | From | David Howells <> | Date | Fri, 18 Sep 2015 11:45:22 +0100 |
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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> ---
fs/overlayfs/copy_up.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 89b4cb3773d7..d3a5990fd2b9 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -270,7 +270,7 @@ out: out_cleanup: ovl_cleanup(wdir, newdentry); - goto out; + goto out2; } /*
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