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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2018-04-23 11:21:03 +0900 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-05-03 09:36:24 -0600 |
| commit | f53823c18131e755905b4f654196fd2cc3953f6e (patch) | |
| tree | 94a1ced15776f1ec274d53b337f5640201b32265 /mm/backing-dev.c | |
| parent | 8236b0ae31c837d2b3a2565c5f8d77f637e824cc (diff) | |
| download | linux-f53823c18131e755905b4f654196fd2cc3953f6e.tar.gz linux-f53823c18131e755905b4f654196fd2cc3953f6e.tar.bz2 linux-f53823c18131e755905b4f654196fd2cc3953f6e.zip | |
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>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'mm/backing-dev.c')
| -rw-r--r-- | mm/backing-dev.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index fa5e6d7406d1..7441bd93b732 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -115,6 +115,7 @@ static int bdi_debug_register(struct backing_dev_info *bdi, const char *name) bdi, &bdi_debug_stats_fops); if (!bdi->debug_stats) { debugfs_remove(bdi->debug_dir); + bdi->debug_dir = NULL; return -ENOMEM; } |