| Message ID | 20221018021851.2900-1-yin31149@gmail.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2] Bluetooth: L2CAP: Fix memory leak in vhci_write | expand |
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 --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) {
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(-)