[PATCH v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg

[PATCH v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg

[Hyunwoo Kim]

This can cause a race with bt_sock_ioctl() because
bt_sock_recvmsg() gets the skb from sk->sk_receive_queue
and then frees it without holding lock_sock.
A use-after-free for a skb occurs with the following flow.
```
bt_sock_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
bt_sock_ioctl() -> skb_peek()
```
Add lock_sock to bt_sock_recvmsg() to fix this issue.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
---
v1 -> v2: Remove duplicate release_sock()s
---
 net/bluetooth/af_bluetooth.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index 336a76165454..b93464ac3517 100644
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -309,11 +309,14 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 	if (flags & MSG_OOB)
 		return -EOPNOTSUPP;
 
+	lock_sock(sk);
+
 	skb = skb_recv_datagram(sk, flags, &err);
 	if (!skb) {
 		if (sk->sk_shutdown & RCV_SHUTDOWN)
-			return 0;
+			err = 0;
 
+		release_sock(sk);
 		return err;
 	}
 
@@ -343,6 +346,8 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
 	skb_free_datagram(sk, skb);
 
+	release_sock(sk);
+
 	if (flags & MSG_TRUNC)
 		copied = skblen;
 
-- 
2.25.1

RE: [v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 1666 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=808455

---Test result---

Test Summary:
CheckPatch                    PASS      0.65 seconds
GitLint                       PASS      1.39 seconds
SubjectPrefix                 PASS      0.63 seconds
BuildKernel                   PASS      26.92 seconds
CheckAllWarning               PASS      30.69 seconds
CheckSparse                   WARNING   35.03 seconds
CheckSmatch                   PASS      98.43 seconds
BuildKernel32                 PASS      26.94 seconds
TestRunnerSetup               PASS      429.62 seconds
TestRunner_l2cap-tester       PASS      23.37 seconds
TestRunner_iso-tester         PASS      45.83 seconds
TestRunner_bnep-tester        PASS      6.95 seconds
TestRunner_mgmt-tester        PASS      162.57 seconds
TestRunner_rfcomm-tester      PASS      10.76 seconds
TestRunner_sco-tester         PASS      14.44 seconds
TestRunner_ioctl-tester       PASS      11.75 seconds
TestRunner_mesh-tester        PASS      8.64 seconds
TestRunner_smp-tester         PASS      9.63 seconds
TestRunner_userchan-tester    PASS      7.28 seconds
IncrementalBuild              PASS      25.21 seconds

Details
##############################
Test: CheckSparse - WARNING
Desc: Run sparse tool with linux kernel
Output:
net/bluetooth/af_bluetooth.c:223:25: warning: context imbalance in 'bt_accept_enqueue' - different lock contexts for basic block


---
Regards,
Linux Bluetooth

Re: [PATCH v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Sat, 9 Dec 2023 05:55:18 -0500 you wrote:
> This can cause a race with bt_sock_ioctl() because
> bt_sock_recvmsg() gets the skb from sk->sk_receive_queue
> and then frees it without holding lock_sock.
> A use-after-free for a skb occurs with the following flow.
> ```
> bt_sock_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
> bt_sock_ioctl() -> skb_peek()
> ```
> Add lock_sock to bt_sock_recvmsg() to fix this issue.
> 
> [...]

Here is the summary with links:
  - [v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg
    https://git.kernel.org/bluetooth/bluetooth-next/c/63b55655d30b

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg

[Martyn Welch]

Hi Hyunwoo,

I've been looking into a few CVEs, the one of interest in this case is 
CVE-2024-21803.

There seems to be little publicly available information about this CVE, 
however the title of this patch and the affected kernel range suggest 
this may be a fix for this CVE.

Would you be able to clarify whether this is a fix for CVE-2024-21803?

Thanks,

Martyn

On 09/12/2023 10:55, Hyunwoo Kim wrote:
> This can cause a race with bt_sock_ioctl() because
> bt_sock_recvmsg() gets the skb from sk->sk_receive_queue
> and then frees it without holding lock_sock.
> A use-after-free for a skb occurs with the following flow.
> ```
> bt_sock_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
> bt_sock_ioctl() -> skb_peek()
> ```
> Add lock_sock to bt_sock_recvmsg() to fix this issue.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
> ---
> v1 -> v2: Remove duplicate release_sock()s
> ---
>   net/bluetooth/af_bluetooth.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
> index 336a76165454..b93464ac3517 100644
> --- a/net/bluetooth/af_bluetooth.c
> +++ b/net/bluetooth/af_bluetooth.c
> @@ -309,11 +309,14 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>   	if (flags & MSG_OOB)
>   		return -EOPNOTSUPP;
>   
> +	lock_sock(sk);
> +
>   	skb = skb_recv_datagram(sk, flags, &err);
>   	if (!skb) {
>   		if (sk->sk_shutdown & RCV_SHUTDOWN)
> -			return 0;
> +			err = 0;
>   
> +		release_sock(sk);
>   		return err;
>   	}
>   
> @@ -343,6 +346,8 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>   
>   	skb_free_datagram(sk, skb);
>   
> +	release_sock(sk);
> +
>   	if (flags & MSG_TRUNC)
>   		copied = skblen;
>   

Re: [PATCH v2] Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg

[Hyunwoo Kim]

Dear Martyn Welch,

I apologize for the long delay in responding.


On Thu, Feb 22, 2024 at 11:23:05AM +0000, Martyn Welch wrote:
> Hi Hyunwoo,
> 
> I've been looking into a few CVEs, the one of interest in this case is
> CVE-2024-21803.
> 
> There seems to be little publicly available information about this CVE,
> however the title of this patch and the affected kernel range suggest this
> may be a fix for this CVE.
This patch is for CVE-2023-51779. 

> 
> Would you be able to clarify whether this is a fix for CVE-2024-21803?
IMO, CVE-2024-21803 appears to be the same vulnerability as CVE-2023-51779. 
It appears to be a duplicate CVE that was registered due to an unknown reporter's mistake.


Best Regards,
Hyunwoo Kim
> 
> Thanks,
> 
> Martyn
> 
> On 09/12/2023 10:55, Hyunwoo Kim wrote:
> > This can cause a race with bt_sock_ioctl() because
> > bt_sock_recvmsg() gets the skb from sk->sk_receive_queue
> > and then frees it without holding lock_sock.
> > A use-after-free for a skb occurs with the following flow.
> > ```
> > bt_sock_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
> > bt_sock_ioctl() -> skb_peek()
> > ```
> > Add lock_sock to bt_sock_recvmsg() to fix this issue.
> > 
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
> > ---
> > v1 -> v2: Remove duplicate release_sock()s
> > ---
> >   net/bluetooth/af_bluetooth.c | 7 ++++++-
> >   1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
> > index 336a76165454..b93464ac3517 100644
> > --- a/net/bluetooth/af_bluetooth.c
> > +++ b/net/bluetooth/af_bluetooth.c
> > @@ -309,11 +309,14 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> >   	if (flags & MSG_OOB)
> >   		return -EOPNOTSUPP;
> > +	lock_sock(sk);
> > +
> >   	skb = skb_recv_datagram(sk, flags, &err);
> >   	if (!skb) {
> >   		if (sk->sk_shutdown & RCV_SHUTDOWN)
> > -			return 0;
> > +			err = 0;
> > +		release_sock(sk);
> >   		return err;
> >   	}
> > @@ -343,6 +346,8 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> >   	skb_free_datagram(sk, skb);
> > +	release_sock(sk);
> > +
> >   	if (flags & MSG_TRUNC)
> >   		copied = skblen;