From: Alan Stern <stern@rowland.harvard.edu>
To: syzbot <syzbot+56f9673bb4cdcbeb0e92@syzkaller.appspotmail.com>,
Andrey Konovalov <andreyknvl@google.com>
Cc: arnd@arndb.de, <gregkh@linuxfoundation.org>,
<jrdr.linux@gmail.com>, <keescook@chromium.org>,
<kstewart@linuxfoundation.org>,
Kernel development list <linux-kernel@vger.kernel.org>,
USB list <linux-usb@vger.kernel.org>,
<syzkaller-bugs@googlegroups.com>, <tglx@linutronix.de>,
<viro@zeniv.linux.org.uk>, <zaitcev@redhat.com>
Subject: Re: Re: Re: possible deadlock in mon_bin_vma_fault
Date: Sun, 24 Nov 2019 10:59:42 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1911241052300.26037-100000@netrider.rowland.org> (raw)
In-Reply-To: <00000000000046a8b6059806b796@google.com>
On Sat, 23 Nov 2019, syzbot wrote:
> > On Fri, 22 Nov 2019, syzbot wrote:
>
> >> > #syz test: linux-4.19.y f6e27dbb1afa
>
> >> "linux-4.19.y" does not look like a valid git repo address.
>
> > Let's try again. The "git tree" value in the original bug report was
> > "upstream", so I'll use that even though it doesn't look like a valid
> > git repo address either.
>
> > Alan Stern
>
> > #syz test: upstream f6e27dbb1afa
>
> "upstream" does not look like a valid git repo address.
Andrey, can you do something about that? It would be a lot nicer if
_all_ the syzbot output and records included an actual git repo address
in the appropriate places.
Alan Stern
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git v5.3
commit 5252eb4c8297fedbf1c5f1e67da44efe00e6ef6b
Author: Pete Zaitcev <zaitcev@kotori.zaitcev.us>
Date: Thu Nov 21 17:24:00 2019 -0600
usb: Fix a deadlock in usbmon between mmap and read
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Reported-by: syzbot+56f9673bb4cdcbeb0e92@syzkaller.appspotmail.com
diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
index ac2b4fcc265f..f48a23adbc35 100644
--- a/drivers/usb/mon/mon_bin.c
+++ b/drivers/usb/mon/mon_bin.c
@@ -1039,12 +1039,18 @@ static long mon_bin_ioctl(struct file *file, unsigned int cmd, unsigned long arg
mutex_lock(&rp->fetch_lock);
spin_lock_irqsave(&rp->b_lock, flags);
- mon_free_buff(rp->b_vec, rp->b_size/CHUNK_SIZE);
- kfree(rp->b_vec);
- rp->b_vec = vec;
- rp->b_size = size;
- rp->b_read = rp->b_in = rp->b_out = rp->b_cnt = 0;
- rp->cnt_lost = 0;
+ if (rp->mmap_active) {
+ mon_free_buff(vec, size/CHUNK_SIZE);
+ kfree(vec);
+ ret = -EBUSY;
+ } else {
+ mon_free_buff(rp->b_vec, rp->b_size/CHUNK_SIZE);
+ kfree(rp->b_vec);
+ rp->b_vec = vec;
+ rp->b_size = size;
+ rp->b_read = rp->b_in = rp->b_out = rp->b_cnt = 0;
+ rp->cnt_lost = 0;
+ }
spin_unlock_irqrestore(&rp->b_lock, flags);
mutex_unlock(&rp->fetch_lock);
}
@@ -1216,13 +1222,21 @@ mon_bin_poll(struct file *file, struct poll_table_struct *wait)
static void mon_bin_vma_open(struct vm_area_struct *vma)
{
struct mon_reader_bin *rp = vma->vm_private_data;
+ unsigned long flags;
+
+ spin_lock_irqsave(&rp->b_lock, flags);
rp->mmap_active++;
+ spin_unlock_irqrestore(&rp->b_lock, flags);
}
static void mon_bin_vma_close(struct vm_area_struct *vma)
{
+ unsigned long flags;
+
struct mon_reader_bin *rp = vma->vm_private_data;
+ spin_lock_irqsave(&rp->b_lock, flags);
rp->mmap_active--;
+ spin_unlock_irqrestore(&rp->b_lock, flags);
}
/*
@@ -1234,16 +1248,12 @@ static vm_fault_t mon_bin_vma_fault(struct vm_fault *vmf)
unsigned long offset, chunk_idx;
struct page *pageptr;
- mutex_lock(&rp->fetch_lock);
offset = vmf->pgoff << PAGE_SHIFT;
- if (offset >= rp->b_size) {
- mutex_unlock(&rp->fetch_lock);
+ if (offset >= rp->b_size)
return VM_FAULT_SIGBUS;
- }
chunk_idx = offset / CHUNK_SIZE;
pageptr = rp->b_vec[chunk_idx].pg;
get_page(pageptr);
- mutex_unlock(&rp->fetch_lock);
vmf->page = pageptr;
return 0;
}
next prev parent reply other threads:[~2019-11-24 15:59 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-03 22:01 possible deadlock in mon_bin_vma_fault syzbot
2019-11-20 12:01 ` syzbot
2019-11-20 16:14 ` Alan Stern
2019-11-20 17:12 ` Pete Zaitcev
2019-11-20 18:47 ` Alan Stern
2019-11-21 14:48 ` Pete Zaitcev
2019-11-21 16:20 ` Alan Stern
2019-11-21 16:46 ` Pete Zaitcev
2019-11-21 23:38 ` Pete Zaitcev
2019-11-22 7:18 ` Dmitry Vyukov
2019-11-22 15:27 ` Alan Stern
2019-11-22 20:52 ` Pete Zaitcev
2019-11-22 22:13 ` Alan Stern
2019-11-22 22:13 ` syzbot
2019-11-23 17:18 ` Alan Stern
2019-11-23 17:18 ` syzbot
2019-11-24 15:59 ` Alan Stern [this message]
2019-11-24 19:10 ` syzbot
2019-11-24 20:55 ` Alan Stern
2019-11-24 23:24 ` syzbot
2019-11-25 0:10 ` Pete Zaitcev
2019-11-25 2:12 ` Alan Stern
2019-11-23 17:18 ` Re: " syzbot
2019-11-22 22:13 ` syzbot
2019-11-20 17:33 ` Pete Zaitcev
2019-11-20 18:18 ` Alan Stern
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