diff mbox series

[v2] Bluetooth: L2CAP: Fix memory leak in vhci_write

Message ID 20221018021851.2900-1-yin31149@gmail.com
State New
Headers
Series [v2] Bluetooth: L2CAP: Fix memory leak in vhci_write |

Commit Message

Hawkins Jiawei Oct. 18, 2022, 2:18 a.m. UTC 
  Syzkaller reports a memory leak as follows:
====================================
BUG: memory leak
unreferenced object 0xffff88810d81ac00 (size 240):
  [...]
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff838733d9>] __alloc_skb+0x1f9/0x270 net/core/skbuff.c:418
    [<ffffffff833f742f>] alloc_skb include/linux/skbuff.h:1257 [inline]
    [<ffffffff833f742f>] bt_skb_alloc include/net/bluetooth/bluetooth.h:469 [inline]
    [<ffffffff833f742f>] vhci_get_user drivers/bluetooth/hci_vhci.c:391 [inline]
    [<ffffffff833f742f>] vhci_write+0x5f/0x230 drivers/bluetooth/hci_vhci.c:511
    [<ffffffff815e398d>] call_write_iter include/linux/fs.h:2192 [inline]
    [<ffffffff815e398d>] new_sync_write fs/read_write.c:491 [inline]
    [<ffffffff815e398d>] vfs_write+0x42d/0x540 fs/read_write.c:578
    [<ffffffff815e3cdd>] ksys_write+0x9d/0x160 fs/read_write.c:631
    [<ffffffff845e0645>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<ffffffff845e0645>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
    [<ffffffff84600087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
====================================

HCI core will uses hci_rx_work() to process frame, which is queued to
the hdev->rx_q tail in hci_recv_frame() by HCI driver.

Yet the problem is that, HCI core may not free the skb after handling
ACL data packets. To be more specific, when start fragment does not
contain the L2CAP length, HCI core just copies skb into conn->rx_skb and
finishes frame process in l2cap_recv_acldata(), without freeing the skb,
which triggers the above memory leak.

This patch solves it by releasing the relative skb, after processing
the above case in l2cap_recv_acldata().
[Thanks Luiz Augusto von Dentz for his suggestion on using break]

Fixes: 4d7ea8ee90e4 ("Bluetooth: L2CAP: Fix handling fragmented length")
Link: https://lore.kernel.org/all/0000000000000d0b1905e6aaef64@google.com/
Reported-and-tested-by: syzbot+8f819e36e01022991cfa@syzkaller.appspotmail.com
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
---
v2:
  - refactor the commit message on the problem description
  - refactor the goto drop with break, suggested by
Luiz Augusto von Dentz

v1:
  https://lore.kernel.org/all/20221017074432.12177-1-yin31149@gmail.com/

 net/bluetooth/l2cap_core.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Comments

patchwork-bot+bluetooth@kernel.org Oct. 18, 2022, 8 p.m. UTC | #1 
Hello:

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

On Tue, 18 Oct 2022 10:18:51 +0800 you wrote:
> Syzkaller reports a memory leak as follows:
> ====================================
> BUG: memory leak
> unreferenced object 0xffff88810d81ac00 (size 240):
>   [...]
>   hex dump (first 32 bytes):
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff838733d9>] __alloc_skb+0x1f9/0x270 net/core/skbuff.c:418
>     [<ffffffff833f742f>] alloc_skb include/linux/skbuff.h:1257 [inline]
>     [<ffffffff833f742f>] bt_skb_alloc include/net/bluetooth/bluetooth.h:469 [inline]
>     [<ffffffff833f742f>] vhci_get_user drivers/bluetooth/hci_vhci.c:391 [inline]
>     [<ffffffff833f742f>] vhci_write+0x5f/0x230 drivers/bluetooth/hci_vhci.c:511
>     [<ffffffff815e398d>] call_write_iter include/linux/fs.h:2192 [inline]
>     [<ffffffff815e398d>] new_sync_write fs/read_write.c:491 [inline]
>     [<ffffffff815e398d>] vfs_write+0x42d/0x540 fs/read_write.c:578
>     [<ffffffff815e3cdd>] ksys_write+0x9d/0x160 fs/read_write.c:631
>     [<ffffffff845e0645>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>     [<ffffffff845e0645>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>     [<ffffffff84600087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
> ====================================
> 
> [...]

Here is the summary with links:
  - [v2] Bluetooth: L2CAP: Fix memory leak in vhci_write
    https://git.kernel.org/bluetooth/bluetooth-next/c/97097c85c088

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 1f34b82ca0ec..f0fb234c2e54 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -8426,9 +8426,8 @@  void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
 		 * expected length.
 		 */
 		if (skb->len < L2CAP_LEN_SIZE) {
-			if (l2cap_recv_frag(conn, skb, conn->mtu) < 0)
-				goto drop;
-			return;
+			l2cap_recv_frag(conn, skb, conn->mtu);
+			break;
 		}
 
 		len = get_unaligned_le16(skb->data) + L2CAP_HDR_SIZE;
@@ -8472,7 +8471,7 @@  void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
 
 			/* Header still could not be read just continue */
 			if (conn->rx_skb->len < L2CAP_LEN_SIZE)
-				return;
+				break;
 		}
 
 		if (skb->len > conn->rx_len) {