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From: Hawkins Jiawei <yin31149@gmail.com>
To: syzbot+8f819e36e01022991cfa@syzkaller.appspotmail.com,
Marcel Holtmann <marcel@holtmann.org>,
Johan Hedberg <johan.hedberg@gmail.com>,
Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, 18801353760@163.com,
yin31149@gmail.com,
Luiz Augusto von Dentz <luiz.von.dentz@intel.com>,
netdev@vger.kernel.org
Subject: [PATCH] Bluetooth: L2CAP: Fix memory leak in vhci_write
Date: Mon, 17 Oct 2022 15:44:32 +0800
Message-Id: <20221017074432.12177-1-yin31149@gmail.com>
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| Series |
Bluetooth: L2CAP: Fix memory leak in vhci_write
|
|
Commit Message
Hawkins Jiawei
Oct. 17, 2022, 7:44 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 does 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 reads possible bytes 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()
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>
---
net/bluetooth/l2cap_core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
Comments
Hi Hawkins, On Mon, Oct 17, 2022 at 12:47 AM Hawkins Jiawei <yin31149@gmail.com> 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 > ==================================== > > 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 does 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 reads possible bytes 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() > > 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> > --- > net/bluetooth/l2cap_core.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > index 1f34b82ca0ec..e0a00854c02e 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); > + goto drop; Let us use break; instead of goto drop since we have copied the skb into rx_sbk. > } > > 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; > + goto drop; > } > > if (skb->len > conn->rx_len) { > -- > 2.25.1 >
On Tue, 18 Oct 2022 at 04:01, Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote: > > Hi Hawkins, > > On Mon, Oct 17, 2022 at 12:47 AM Hawkins Jiawei <yin31149@gmail.com> 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 > > ==================================== > > > > 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 does 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 reads possible bytes 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() > > > > 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> > > --- > > net/bluetooth/l2cap_core.c | 7 +++---- > > 1 file changed, 3 insertions(+), 4 deletions(-) > > > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > > index 1f34b82ca0ec..e0a00854c02e 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); > > + goto drop; > > Let us use break; instead of goto drop since we have copied the skb into rx_sbk. Thanks for your suggestion. I will refactor this patch as you suggested. > > > } > > > > 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; > > + goto drop; > > } > > > > if (skb->len > conn->rx_len) { > > -- > > 2.25.1 > > > > > -- > Luiz Augusto von Dentz
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 1f34b82ca0ec..e0a00854c02e 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); + goto drop; } 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; + goto drop; } if (skb->len > conn->rx_len) {