From: Alexey Gladkov <gladkov.alexey@gmail.com>
To: ebiederm@xmission.com
Cc: syzbot <syzbot+4abac52934a48af5ff19@syzkaller.appspotmail.com>,
adobriyan@gmail.com, keescook@chromium.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk
Subject: [PATCH] proc: s_fs_info may be NULL when proc_kill_sb is called
Date: Wed, 10 Jun 2020 15:04:22 +0200 [thread overview]
Message-ID: <20200610130422.1197386-1-gladkov.alexey@gmail.com> (raw)
In-Reply-To: <0000000000002d7ca605a7b8b1c5@google.com>
syzbot found that proc_fill_super() fails before filling up sb->s_fs_info,
deactivate_locked_super() will be called and sb->s_fs_info will be NULL.
The proc_kill_sb() does not expect fs_info to be NULL which is wrong.
Link: https://lore.kernel.org/lkml/0000000000002d7ca605a7b8b1c5@google.com
Reported-by: syzbot+4abac52934a48af5ff19@syzkaller.appspotmail.com
Fixes: fa10fed30f25 ("proc: allow to mount many instances of proc in one pid namespace")
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
---
fs/proc/root.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/fs/proc/root.c b/fs/proc/root.c
index ffebed1999e5..a715eb9f196a 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -264,15 +264,18 @@ static void proc_kill_sb(struct super_block *sb)
{
struct proc_fs_info *fs_info = proc_sb_info(sb);
- if (fs_info->proc_self)
- dput(fs_info->proc_self);
+ if (fs_info) {
+ if (fs_info->proc_self)
+ dput(fs_info->proc_self);
- if (fs_info->proc_thread_self)
- dput(fs_info->proc_thread_self);
+ if (fs_info->proc_thread_self)
+ dput(fs_info->proc_thread_self);
+
+ put_pid_ns(fs_info->pid_ns);
+ kfree(fs_info);
+ }
kill_anon_super(sb);
- put_pid_ns(fs_info->pid_ns);
- kfree(fs_info);
}
static struct file_system_type proc_fs_type = {
--
2.25.4
next prev parent reply other threads:[~2020-06-10 13:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 10:56 general protection fault in proc_kill_sb syzbot
2020-06-10 11:23 ` Tetsuo Handa
2020-06-10 11:44 ` Alexey Gladkov
2020-06-10 13:04 ` Alexey Gladkov [this message]
2020-06-10 17:12 ` [PATCH] proc: s_fs_info may be NULL when proc_kill_sb is called Eric W. Biederman
2020-06-10 17:41 ` Al Viro
2020-06-10 18:35 ` [PATCH v2] " Alexey Gladkov
2020-06-10 20:17 ` Eric W. Biederman
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