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Date: Mon, 15 Aug 2022 08:59:11 +0800 From: Dongliang Mu <mudongliangabcd@...il.com> To: Christian Brauner <brauner@...nel.org> Cc: Dongliang Mu <dzm91@...t.edu.cn>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Arve Hjønnevåg <arve@...roid.com>, Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>, Joel Fernandes <joel@...lfernandes.org>, Carlos Llamas <cmllamas@...gle.com>, Suren Baghdasaryan <surenb@...gle.com>, Kees Cook <keescook@...omium.org>, syzkaller <syzkaller@...glegroups.com>, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] drivers: binderfs: fix memory leak in binderfs_fill_super On Fri, Aug 12, 2022 at 10:18 PM Christian Brauner <brauner@...nel.org> wrote: > > On Fri, Aug 12, 2022 at 09:48:40PM +0800, Dongliang Mu wrote: > > On Fri, Aug 12, 2022 at 9:41 PM Christian Brauner <brauner@...nel.org> wrote: > > > > > > On Fri, Aug 12, 2022 at 09:21:24PM +0800, Dongliang Mu wrote: > > > > From: Dongliang Mu <mudongliangabcd@...il.com> > > > > > > > > In binderfs_fill_super, if s_root is not successfully initialized by > > > > d_make_root, the previous allocated s_sb_info will not be freed since > > > > generic_shutdown_super first checks if sb->s_root and then does > > > > put_super operation. The put_super operation calls binderfs_put_super > > > > to deallocate s_sb_info and put ipc_ns. This will lead to memory leak > > > > in binderfs_fill_super. > > > > > > > > Fix this by invoking binderfs_put_super at error sites before s_root > > > > is successfully initialized. > > > > > > > > Fixes: 095cf502b31e ("binderfs: port to new mount api") > > > > Reported-by: syzkaller <syzkaller@...glegroups.com> > > > > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com> > > > > --- > > > > > > Seems right but where's the full syzbot link to the issue? > > > Also, wouldn't (untested) sm like the below be better?: > > > > I originally would like to change the order to object initialization, > > but I am not sure if they can be exchanged since many *_fill_super are > > ended with d_make_root. > > > > If you are sure about this exchange, I can resubmit a v2 patch. > > I think we should just always clean up the allocated memory in > binderfs_fill_super() when d_make_root() fails and before via a goto > block after the successful return. So we keep the cleanup in > binderfs_fill_super() consistent and restricted to a single location. Hi Christian, So the final decision is to keep the cleanup or error handling code in a single goto location at the end of binderfs_fill_super. If I understand correctly, this change keeps the same semantic as mine but is more elegant to maintain.
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