Bluetooth: hci_core: remove acl hdr handle error message

[PATCH] Bluetooth: hci_core: remove acl hdr handle error message

Posted by Edward Adam Davis 1 month, 2 weeks ago

Syzbot reported a uninit-value in hci_rx_work.This is because l2cap didn't
execute the corresponding connection request to call l2cap_send_cmd() or
l2cap_do_send(), and ultimately called hci_add_acl_hdr() to set hdr->handle.

Therefore, when calling the thread callback function hci_rx_work() to call
hci_acldata_packet, hdr->handle should not be used directly.

Reported-and-tested-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 net/bluetooth/hci_core.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index d6976db02c06..20605a7f3f4e 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3791,8 +3791,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 		l2cap_recv_acldata(conn, skb, flags);
 		return;
 	} else {
-		bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
-			   handle);
+		bt_dev_err(hdev, "ACL packet for unknown connection handle");
 	}
 
 	kfree_skb(skb);
-- 
2.43.0

Re: [PATCH] Bluetooth: hci_core: remove acl hdr handle error message

Posted by Luiz Augusto von Dentz 1 month, 2 weeks ago

Hi Edward,

On Tue, Oct 8, 2024 at 6:47 AM Edward Adam Davis <eadavis@qq.com> wrote:
>
> Syzbot reported a uninit-value in hci_rx_work.This is because l2cap didn't
> execute the corresponding connection request to call l2cap_send_cmd() or
> l2cap_do_send(), and ultimately called hci_add_acl_hdr() to set hdr->handle.

What are you talking about here, what these functions have to do with
a local handle variable?

> Therefore, when calling the thread callback function hci_rx_work() to call
> hci_acldata_packet, hdr->handle should not be used directly.

It is not being used directly, the handle is a local variable which
get assigned:

    handle = __le16_to_cpu(hdr->handle);

If what you are saying is that there is no guarantee that skb->len >=
HCI_ACL_HDR_SIZE then we probably want to replace skb_pull with
skb_pull_data.

> Reported-and-tested-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  net/bluetooth/hci_core.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index d6976db02c06..20605a7f3f4e 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -3791,8 +3791,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
>                 l2cap_recv_acldata(conn, skb, flags);
>                 return;
>         } else {
> -               bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
> -                          handle);
> +               bt_dev_err(hdev, "ACL packet for unknown connection handle");
>         }
>
>         kfree_skb(skb);
> --
> 2.43.0
>


-- 
Luiz Augusto von Dentz

Re: [PATCH] Bluetooth: hci_core: remove acl hdr handle error message

Posted by Edward Adam Davis 1 month, 2 weeks ago

On Tue, 8 Oct 2024 10:12:34 -0400, Luiz Augusto von Dentz wrote:
> On Tue, Oct 8, 2024 at 6:47 AM Edward Adam Davis <eadavis@qq.com> wrote:
> >
> > Syzbot reported a uninit-value in hci_rx_work.This is because l2cap didn't
> > execute the corresponding connection request to call l2cap_send_cmd() or
> > l2cap_do_send(), and ultimately called hci_add_acl_hdr() to set hdr->handle.
> 
> What are you talking about here, what these functions have to do with
> a local handle variable?
> 
> > Therefore, when calling the thread callback function hci_rx_work() to call
> > hci_acldata_packet, hdr->handle should not be used directly.
> 
> It is not being used directly, the handle is a local variable which
> get assigned:
> 
>     handle = __le16_to_cpu(hdr->handle);
> 
> If what you are saying is that there is no guarantee that skb->len >=
> HCI_ACL_HDR_SIZE then we probably want to replace skb_pull with
> skb_pull_data.
You are right, skb->len is too small.
But, skb_pull is ok, maybe just need to add a check.

#syz test

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index d6976db02c06..cfb828452a13 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3769,7 +3769,11 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 	struct hci_conn *conn;
 	__u16 handle, flags;
 
-	skb_pull(skb, HCI_ACL_HDR_SIZE);
+	if (!skb_pull(skb, HCI_ACL_HDR_SIZE)) {
+		BT_ERR("ACL data packet %d, smaller than ACL HEADER Size %d\n",
+			skb->len, HCI_ACL_HDR_SIZE);
+		goto out;
+	}
 
 	handle = __le16_to_cpu(hdr->handle);
 	flags  = hci_flags(handle);
@@ -3795,6 +3799,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 			   handle);
 	}
 
+out:
 	kfree_skb(skb);
 }

Re: [syzbot] [bluetooth?] KMSAN: uninit-value in hci_rx_work

Posted by syzbot 1 month, 2 weeks ago

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com
Tested-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com

Tested on:

commit:         75b607fa Merge tag 'sched_ext-for-6.12-rc2-fixes' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1415f380580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=981fe2ff8a1e457a
dashboard link: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12e37707980000

Note: testing is done by a robot and is best-effort only.

Re: [PATCH] Bluetooth: hci_core: remove acl hdr handle error message

Posted by Luiz Augusto von Dentz 1 month, 2 weeks ago

On Tue, Oct 8, 2024 at 10:12 AM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Edward,
>
> On Tue, Oct 8, 2024 at 6:47 AM Edward Adam Davis <eadavis@qq.com> wrote:
> >
> > Syzbot reported a uninit-value in hci_rx_work.This is because l2cap didn't
> > execute the corresponding connection request to call l2cap_send_cmd() or
> > l2cap_do_send(), and ultimately called hci_add_acl_hdr() to set hdr->handle.
>
> What are you talking about here, what these functions have to do with
> a local handle variable?
>
> > Therefore, when calling the thread callback function hci_rx_work() to call
> > hci_acldata_packet, hdr->handle should not be used directly.
>
> It is not being used directly, the handle is a local variable which
> get assigned:
>
>     handle = __le16_to_cpu(hdr->handle);
>
> If what you are saying is that there is no guarantee that skb->len >=
> HCI_ACL_HDR_SIZE then we probably want to replace skb_pull with
> skb_pull_data.
>
> > Reported-and-tested-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
> > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > ---
> >  net/bluetooth/hci_core.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > index d6976db02c06..20605a7f3f4e 100644
> > --- a/net/bluetooth/hci_core.c
> > +++ b/net/bluetooth/hci_core.c
> > @@ -3791,8 +3791,7 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
> >                 l2cap_recv_acldata(conn, skb, flags);
> >                 return;
> >         } else {
> > -               bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
> > -                          handle);
> > +               bt_dev_err(hdev, "ACL packet for unknown connection handle");
> >         }
> >
> >         kfree_skb(skb);
> > --
> > 2.43.0
> >
>
>
> --
> Luiz Augusto von Dentz

#syz test

-- 
Luiz Augusto von Dentz

Re: [syzbot] [bluetooth?] KMSAN: uninit-value in hci_rx_work

Posted by syzbot 1 month, 2 weeks ago

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com
Tested-by: syzbot+6ea290ba76d8c1eb1ac2@syzkaller.appspotmail.com

Tested on:

commit:         87d6aab2 Merge tag 'for_linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14bf8f9f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=981fe2ff8a1e457a
dashboard link: https://syzkaller.appspot.com/bug?extid=6ea290ba76d8c1eb1ac2
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14f41780580000

Note: testing is done by a robot and is best-effort only.