From: Hillf Danton <hdanton@sina.com>
To: syzbot <syzbot+5d34cc6474499a5ff516@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [ntfs3?] KASAN: slab-use-after-free Read in chrdev_open
Date: Sat, 27 Apr 2024 18:44:25 +0800 [thread overview]
Message-ID: <20240427104425.3926-1-hdanton@sina.com> (raw)
In-Reply-To: <000000000000f386f90616fea5ef@google.com>
On Fri, 26 Apr 2024 05:00:21 -0700
> syzbot found the following issue on:
>
> HEAD commit: e33c4963bf53 Merge tag 'nfsd-6.9-5' of git://git.kernel.or..
> git tree: upstream
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12499380980000
#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git e33c4963bf53
--- x/fs/char_dev.c
+++ y/fs/char_dev.c
@@ -377,6 +377,9 @@ static int chrdev_open(struct inode *ino
struct cdev *new = NULL;
int ret = 0;
+ if (!igrab(inode))
+ return -ENXIO;
+
spin_lock(&cdev_lock);
p = inode->i_cdev;
if (!p) {
@@ -384,8 +387,10 @@ static int chrdev_open(struct inode *ino
int idx;
spin_unlock(&cdev_lock);
kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
- if (!kobj)
+ if (!kobj) {
+ iput(inode);
return -ENXIO;
+ }
new = container_of(kobj, struct cdev, kobj);
spin_lock(&cdev_lock);
/* Check i_cdev again in case somebody beat us to it while
@@ -401,8 +406,10 @@ static int chrdev_open(struct inode *ino
ret = -ENXIO;
spin_unlock(&cdev_lock);
cdev_put(new);
- if (ret)
+ if (ret) {
+ iput(inode);
return ret;
+ }
ret = -ENXIO;
fops = fops_get(p->ops);
@@ -416,10 +423,12 @@ static int chrdev_open(struct inode *ino
goto out_cdev_put;
}
+ iput(inode);
return 0;
out_cdev_put:
cdev_put(p);
+ iput(inode);
return ret;
}
--
next prev parent reply other threads:[~2024-04-27 10:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 12:00 [syzbot] [ntfs3?] KASAN: slab-use-after-free Read in chrdev_open syzbot
2024-04-26 20:57 ` syzbot
2024-04-27 2:06 ` Hillf Danton
2024-04-27 2:58 ` syzbot
2024-04-27 6:29 ` Hillf Danton
2024-04-27 6:52 ` syzbot
2024-04-27 9:18 ` Hillf Danton
2024-04-27 9:45 ` syzbot
2024-04-27 10:44 ` Hillf Danton [this message]
2024-04-27 10:58 ` syzbot
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