Messages in this thread | | | Date | Mon, 23 Apr 2018 12:37:16 +0200 | From | Greg KH <> | Subject | Re: KASAN: use-after-free Read in debugfs_remove (2) |
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On Mon, Apr 23, 2018 at 07:34:45PM +0900, Tetsuo Handa wrote: > >From be88e559ec13f49b1c3aec2457c14c70f6b1926a Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Date: Mon, 23 Apr 2018 11:21:03 +0900 > Subject: [PATCH] bdi: Fix use after free bug in debugfs_remove() > > syzbot is reporting use after free bug in debugfs_remove() [1]. > > This is because fault injection made memory allocation for > debugfs_create_file() from bdi_debug_register() from bdi_register_va() > fail and continued with setting WB_registered. But when debugfs_remove() > is called from debugfs_remove(bdi->debug_dir) from bdi_debug_unregister() > from bdi_unregister() from release_bdi() because WB_registered was set > by bdi_register_va(), IS_ERR_OR_NULL(bdi->debug_dir) == false despite > debugfs_remove(bdi->debug_dir) was already called from bdi_register_va(). > > Fix this by making IS_ERR_OR_NULL(bdi->debug_dir) == true. > > [1] https://syzkaller.appspot.com/bug?id=5ab4efd91a96dcea9b68104f159adf4af2a6dfc1 > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Reported-by: syzbot <syzbot+049cb4ae097049dac137@syzkaller.appspotmail.com> > Fixes: 97f07697932e6faf ("bdi: convert bdi_debug_register to int") > Cc: weiping zhang <zhangweiping@didichuxing.com> > Cc: Jan Kara <jack@suse.cz> > Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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