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    SubjectRe: [PATCH] drivers: binderfs: fix memory leak in binderfs_fill_super
    On Fri, Aug 12, 2022 at 10:18 PM Christian Brauner <brauner@kernel.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@kernel.org> wrote:
    > > >
    > > > On Fri, Aug 12, 2022 at 09:21:24PM +0800, Dongliang Mu wrote:
    > > > > From: Dongliang Mu <mudongliangabcd@gmail.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@googlegroups.com>
    > > > > Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.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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