2022-01-13 15:09:05

by Radosław Biernacki

[permalink] [raw]
Subject: [PATCH] Bluetooth: Fix skb allocation in mgmt_remote_name()

From: Radoslaw Biernacki <[email protected]>

This patch fixes skb allocation, as lack of space for ev might push skb
tail beyond its end.
Also introduce eir_precalc_len() that can be used instead of magic
numbers for similar eir operations on skb.

Fixes: cf1bce1de7eeb ("Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_FOUND")
Signed-off-by: Angela Czubak <[email protected]>
Signed-off-by: Marek Maslanka <[email protected]>
Signed-off-by: Radoslaw Biernacki <[email protected]>
---
net/bluetooth/eir.h | 5 +++++
net/bluetooth/mgmt.c | 12 ++++--------
2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h
index 05e2e917fc25..e5876751f07e 100644
--- a/net/bluetooth/eir.h
+++ b/net/bluetooth/eir.h
@@ -15,6 +15,11 @@ u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr);
u8 eir_append_local_name(struct hci_dev *hdev, u8 *eir, u8 ad_len);
u8 eir_append_appearance(struct hci_dev *hdev, u8 *ptr, u8 ad_len);

+static inline u16 eir_precalc_len(u8 data_len)
+{
+ return sizeof(u8) * 2 + data_len;
+}
+
static inline u16 eir_append_data(u8 *eir, u16 eir_len, u8 type,
u8 *data, u8 data_len)
{
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 37087cf7dc5a..d517fd847730 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -9680,13 +9680,11 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
{
struct sk_buff *skb;
struct mgmt_ev_device_found *ev;
- u16 eir_len;
- u32 flags;
+ u16 eir_len = 0;
+ u32 flags = 0;

- if (name_len)
- skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 2 + name_len);
- else
- skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 0);
+ skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND,
+ sizeof(*ev) + (name ? eir_precalc_len(name_len) : 0));

ev = skb_put(skb, sizeof(*ev));
bacpy(&ev->addr.bdaddr, bdaddr);
@@ -9696,10 +9694,8 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
if (name) {
eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE, name,
name_len);
- flags = 0;
skb_put(skb, eir_len);
} else {
- eir_len = 0;
flags = MGMT_DEV_FOUND_NAME_REQUEST_FAILED;
}

--
2.34.1.703.g22d0c6ccf7-goog



2022-01-13 16:17:14

by Luiz Augusto von Dentz

[permalink] [raw]
Subject: Re: [PATCH] Bluetooth: Fix skb allocation in mgmt_remote_name()

Hi Radoslaw,

On Thu, Jan 13, 2022 at 7:09 AM Radoslaw Biernacki <[email protected]> wrote:
>
> From: Radoslaw Biernacki <[email protected]>
>
> This patch fixes skb allocation, as lack of space for ev might push skb
> tail beyond its end.
> Also introduce eir_precalc_len() that can be used instead of magic
> numbers for similar eir operations on skb.
>
> Fixes: cf1bce1de7eeb ("Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_FOUND")
> Signed-off-by: Angela Czubak <[email protected]>
> Signed-off-by: Marek Maslanka <[email protected]>
> Signed-off-by: Radoslaw Biernacki <[email protected]>
> ---
> net/bluetooth/eir.h | 5 +++++
> net/bluetooth/mgmt.c | 12 ++++--------
> 2 files changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h
> index 05e2e917fc25..e5876751f07e 100644
> --- a/net/bluetooth/eir.h
> +++ b/net/bluetooth/eir.h
> @@ -15,6 +15,11 @@ u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr);
> u8 eir_append_local_name(struct hci_dev *hdev, u8 *eir, u8 ad_len);
> u8 eir_append_appearance(struct hci_dev *hdev, u8 *ptr, u8 ad_len);
>
> +static inline u16 eir_precalc_len(u8 data_len)
> +{
> + return sizeof(u8) * 2 + data_len;
> +}
> +
> static inline u16 eir_append_data(u8 *eir, u16 eir_len, u8 type,
> u8 *data, u8 data_len)
> {
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 37087cf7dc5a..d517fd847730 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -9680,13 +9680,11 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> {
> struct sk_buff *skb;
> struct mgmt_ev_device_found *ev;
> - u16 eir_len;
> - u32 flags;
> + u16 eir_len = 0;
> + u32 flags = 0;
>
> - if (name_len)
> - skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 2 + name_len);
> - else
> - skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 0);
> + skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND,
> + sizeof(*ev) + (name ? eir_precalc_len(name_len) : 0));

Looks like mgmt_device_connected also has a similar problem.

> ev = skb_put(skb, sizeof(*ev));
> bacpy(&ev->addr.bdaddr, bdaddr);
> @@ -9696,10 +9694,8 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> if (name) {
> eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE, name,
> name_len);
> - flags = 0;
> skb_put(skb, eir_len);
> } else {
> - eir_len = 0;
> flags = MGMT_DEV_FOUND_NAME_REQUEST_FAILED;
> }

These changes would leave flags and eir_len uninitialized.

> --
> 2.34.1.703.g22d0c6ccf7-goog
>


--
Luiz Augusto von Dentz

2022-01-13 22:07:21

by Radosław Biernacki

[permalink] [raw]
Subject: Re: [PATCH] Bluetooth: Fix skb allocation in mgmt_remote_name()

Hi Luiz,

czw., 13 sty 2022 o 17:17 Luiz Augusto von Dentz
<[email protected]> napisał(a):
>
> Hi Radoslaw,
>
> On Thu, Jan 13, 2022 at 7:09 AM Radoslaw Biernacki <[email protected]> wrote:
> >
> > From: Radoslaw Biernacki <[email protected]>
> >
> > This patch fixes skb allocation, as lack of space for ev might push skb
> > tail beyond its end.
> > Also introduce eir_precalc_len() that can be used instead of magic
> > numbers for similar eir operations on skb.
> >
> > Fixes: cf1bce1de7eeb ("Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_FOUND")
> > Signed-off-by: Angela Czubak <[email protected]>
> > Signed-off-by: Marek Maslanka <[email protected]>
> > Signed-off-by: Radoslaw Biernacki <[email protected]>
> > ---
> > net/bluetooth/eir.h | 5 +++++
> > net/bluetooth/mgmt.c | 12 ++++--------
> > 2 files changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h
> > index 05e2e917fc25..e5876751f07e 100644
> > --- a/net/bluetooth/eir.h
> > +++ b/net/bluetooth/eir.h
> > @@ -15,6 +15,11 @@ u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr);
> > u8 eir_append_local_name(struct hci_dev *hdev, u8 *eir, u8 ad_len);
> > u8 eir_append_appearance(struct hci_dev *hdev, u8 *ptr, u8 ad_len);
> >
> > +static inline u16 eir_precalc_len(u8 data_len)
> > +{
> > + return sizeof(u8) * 2 + data_len;
> > +}
> > +
> > static inline u16 eir_append_data(u8 *eir, u16 eir_len, u8 type,
> > u8 *data, u8 data_len)
> > {
> > diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> > index 37087cf7dc5a..d517fd847730 100644
> > --- a/net/bluetooth/mgmt.c
> > +++ b/net/bluetooth/mgmt.c
> > @@ -9680,13 +9680,11 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> > {
> > struct sk_buff *skb;
> > struct mgmt_ev_device_found *ev;
> > - u16 eir_len;
> > - u32 flags;
> > + u16 eir_len = 0;
> > + u32 flags = 0;
> >
> > - if (name_len)
> > - skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 2 + name_len);
> > - else
> > - skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 0);
> > + skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND,
> > + sizeof(*ev) + (name ? eir_precalc_len(name_len) : 0));
>
> Looks like mgmt_device_connected also has a similar problem.

Yes, I was planning to send a patch to this one though it will not be as slick.
It would be nice to have a helper which will call skb_put() and add
eir data at once.
Basically skb operation in pair to, what eir_append_data() does with
help of eir_len but without awkwardness when passing return value to
skb_put() (as it returns offset not size).
I will send V2 with two patches. I hope they will align with your
original goal of eliminating the necessity of intermediary buffers at
some point in future.

>
> > ev = skb_put(skb, sizeof(*ev));
> > bacpy(&ev->addr.bdaddr, bdaddr);
> > @@ -9696,10 +9694,8 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> > if (name) {
> > eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE, name,
> > name_len);
> > - flags = 0;
> > skb_put(skb, eir_len);
> > } else {
> > - eir_len = 0;
> > flags = MGMT_DEV_FOUND_NAME_REQUEST_FAILED;
> > }
>
> These changes would leave flags and eir_len uninitialized.

Both are initialized to 0 by this patch.

>
> > --
> > 2.34.1.703.g22d0c6ccf7-goog
> >
>
>
> --
> Luiz Augusto von Dentz

2022-01-14 14:10:56

by Luiz Augusto von Dentz

[permalink] [raw]
Subject: Re: [PATCH] Bluetooth: Fix skb allocation in mgmt_remote_name()

Hi Radosław,

On Thu, Jan 13, 2022 at 2:07 PM Radosław Biernacki <[email protected]> wrote:
>
> Hi Luiz,
>
> czw., 13 sty 2022 o 17:17 Luiz Augusto von Dentz
> <[email protected]> napisał(a):
> >
> > Hi Radoslaw,
> >
> > On Thu, Jan 13, 2022 at 7:09 AM Radoslaw Biernacki <[email protected]> wrote:
> > >
> > > From: Radoslaw Biernacki <[email protected]>
> > >
> > > This patch fixes skb allocation, as lack of space for ev might push skb
> > > tail beyond its end.
> > > Also introduce eir_precalc_len() that can be used instead of magic
> > > numbers for similar eir operations on skb.
> > >
> > > Fixes: cf1bce1de7eeb ("Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_FOUND")
> > > Signed-off-by: Angela Czubak <[email protected]>
> > > Signed-off-by: Marek Maslanka <[email protected]>
> > > Signed-off-by: Radoslaw Biernacki <[email protected]>
> > > ---
> > > net/bluetooth/eir.h | 5 +++++
> > > net/bluetooth/mgmt.c | 12 ++++--------
> > > 2 files changed, 9 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h
> > > index 05e2e917fc25..e5876751f07e 100644
> > > --- a/net/bluetooth/eir.h
> > > +++ b/net/bluetooth/eir.h
> > > @@ -15,6 +15,11 @@ u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr);
> > > u8 eir_append_local_name(struct hci_dev *hdev, u8 *eir, u8 ad_len);
> > > u8 eir_append_appearance(struct hci_dev *hdev, u8 *ptr, u8 ad_len);
> > >
> > > +static inline u16 eir_precalc_len(u8 data_len)
> > > +{
> > > + return sizeof(u8) * 2 + data_len;
> > > +}
> > > +
> > > static inline u16 eir_append_data(u8 *eir, u16 eir_len, u8 type,
> > > u8 *data, u8 data_len)
> > > {
> > > diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> > > index 37087cf7dc5a..d517fd847730 100644
> > > --- a/net/bluetooth/mgmt.c
> > > +++ b/net/bluetooth/mgmt.c
> > > @@ -9680,13 +9680,11 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> > > {
> > > struct sk_buff *skb;
> > > struct mgmt_ev_device_found *ev;
> > > - u16 eir_len;
> > > - u32 flags;
> > > + u16 eir_len = 0;
> > > + u32 flags = 0;
> > >
> > > - if (name_len)
> > > - skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 2 + name_len);
> > > - else
> > > - skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 0);
> > > + skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND,
> > > + sizeof(*ev) + (name ? eir_precalc_len(name_len) : 0));
> >
> > Looks like mgmt_device_connected also has a similar problem.
>
> Yes, I was planning to send a patch to this one though it will not be as slick.
> It would be nice to have a helper which will call skb_put() and add
> eir data at once.
> Basically skb operation in pair to, what eir_append_data() does with
> help of eir_len but without awkwardness when passing return value to
> skb_put() (as it returns offset not size).

Hmm, that might be a good idea indeed something like eir_append_skb,
if only we could grow the skb with skb_put directly that would
eliminate the problem with having to reserve enough space for the
worse case.

> I will send V2 with two patches. I hope they will align with your
> original goal of eliminating the necessity of intermediary buffers at
> some point in future.
>
> >
> > > ev = skb_put(skb, sizeof(*ev));
> > > bacpy(&ev->addr.bdaddr, bdaddr);
> > > @@ -9696,10 +9694,8 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
> > > if (name) {
> > > eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE, name,
> > > name_len);
> > > - flags = 0;
> > > skb_put(skb, eir_len);
> > > } else {
> > > - eir_len = 0;
> > > flags = MGMT_DEV_FOUND_NAME_REQUEST_FAILED;
> > > }
> >
> > These changes would leave flags and eir_len uninitialized.
>
> Both are initialized to 0 by this patch.

Sorry, I must be blind that I didn't see you had changed that to be
initialized in their declaration.

> >
> > > --
> > > 2.34.1.703.g22d0c6ccf7-goog
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz



--
Luiz Augusto von Dentz