* Re: [PATCH] net/bluetooth: Fix bound check in event handling
2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
@ 2019-03-02 16:46 ` Marcel Holtmann
2019-03-02 23:17 ` Tomas Bortoli
2019-03-04 15:04 ` Dan Carpenter
` (2 subsequent siblings)
3 siblings, 1 reply; 9+ messages in thread
From: Marcel Holtmann @ 2019-03-02 16:46 UTC (permalink / raw)
To: Tomas Bortoli
Cc: Johan Hedberg, David S. Miller, open list:BLUETOOTH DRIVERS,
netdev, linux-kernel, syzkaller
Hi Tomas,
> hci_inquiry_result_with_rssi_evt() can perform out of bound reads
> on skb->data as a bound check is missing.
>
> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
> Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
> ---
> Syzkaler reports:
> https://syzkaller.appspot.com/bug?id=d708485af9edc3af35f3b4d554e827c6c8bf6b0f
> https://syzkaller.appspot.com/bug?id=3acd1155d48a5acc5d76711568b04926945a6885
>
> net/bluetooth/hci_event.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index ac2826ce162b..aa953d23bb72 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -3983,6 +3983,10 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
> for (; num_rsp; num_rsp--, info++) {
> u32 flags;
>
> + if ((void *)(info + sizeof(info)) >
> + (void *)(skb->data + skb->len))
> + break;
> +
first of all, the loop exists twice here. If one is vulnerable, then the second is a well. And second, can we not just do this inside the for-condition check or a lot simpler than this void casting fun.
Regards
Marcel
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] net/bluetooth: Fix bound check in event handling
2019-03-02 16:46 ` Marcel Holtmann
@ 2019-03-02 23:17 ` Tomas Bortoli
0 siblings, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-02 23:17 UTC (permalink / raw)
To: Marcel Holtmann
Cc: Johan Hedberg, David S. Miller, open list:BLUETOOTH DRIVERS,
netdev, linux-kernel, syzkaller
Hi Marcel,
On 3/2/19 5:46 PM, Marcel Holtmann wrote:
> Hi Tomas,
>
>> hci_inquiry_result_with_rssi_evt() can perform out of bound reads
>> on skb->data as a bound check is missing.
>>
>> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
>> Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
>> Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
>> ---
>> Syzkaler reports:
>> https://syzkaller.appspot.com/bug?id=d708485af9edc3af35f3b4d554e827c6c8bf6b0f
>> https://syzkaller.appspot.com/bug?id=3acd1155d48a5acc5d76711568b04926945a6885
>>
>> net/bluetooth/hci_event.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
>> index ac2826ce162b..aa953d23bb72 100644
>> --- a/net/bluetooth/hci_event.c
>> +++ b/net/bluetooth/hci_event.c
>> @@ -3983,6 +3983,10 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
>> for (; num_rsp; num_rsp--, info++) {
>> u32 flags;
>>
>> + if ((void *)(info + sizeof(info)) >
>> + (void *)(skb->data + skb->len))
>> + break;
>> +
>
> first of all, the loop exists twice here. If one is vulnerable, then the second is a well. And second, can we not just do this inside the for-condition check or a lot simpler than this void casting fun.
>
1. The other for loop is not vulnerable because of the `if` that wraps
the loops. Unfortunately the condition only provides bound checking for
the "else" branch.
2. Sure. I was just getting some compiler warning like "calculated value
but unused" when putting the additional condition. By the way I am
curious to see how to avoid this void casting.
Regards,
Tomas
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] net/bluetooth: Fix bound check in event handling
2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
2019-03-02 16:46 ` Marcel Holtmann
@ 2019-03-04 15:04 ` Dan Carpenter
2019-03-04 19:58 ` Tomas Bortoli
2019-03-04 20:20 ` Tomas Bortoli
2019-03-30 7:17 ` Dan Carpenter
3 siblings, 1 reply; 9+ messages in thread
From: Dan Carpenter @ 2019-03-04 15:04 UTC (permalink / raw)
To: kbuild, Tomas Bortoli
Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth, netdev,
linux-kernel, syzkaller, Tomas Bortoli
Hi Tomas,
url: https://github.com/0day-ci/linux/commits/Tomas-Bortoli/net-bluetooth-Fix-bound-check-in-event-handling/20190301-213647
base: https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master
smatch warnings:
net/bluetooth/hci_event.c:3986 hci_inquiry_result_with_rssi_evt() warn: potential pointer math issue ('info' is a 120 bit pointer)
# https://github.com/0day-ci/linux/commit/00305742c021794f147b348d45eb10ea26e5a514
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 00305742c021794f147b348d45eb10ea26e5a514
vim +3986 net/bluetooth/hci_event.c
a9de9248 Marcel Holtmann 2007-10-20 3979 if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
138d22ef Szymon Janc 2011-02-17 3980 struct inquiry_info_with_rssi_and_pscan_mode *info;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
138d22ef Szymon Janc 2011-02-17 3981 info = (void *) (skb->data + 1);
a9de9248 Marcel Holtmann 2007-10-20 3982
e17acd40 Johan Hedberg 2011-03-30 3983 for (; num_rsp; num_rsp--, info++) {
af58925c Marcel Holtmann 2014-07-01 3984 u32 flags;
af58925c Marcel Holtmann 2014-07-01 3985
00305742 Tomas Bortoli 2019-02-28 @3986 if ((void *)(info + sizeof(info)) >
^^^^^^^^^^^^^^^^^^^
This is a pointer math bug. The options to fix it are:
if ((void *)info + sizeof(info) >
Or:
if ((void *)(info + 1) >
00305742 Tomas Bortoli 2019-02-28 3987 (void *)(skb->data + skb->len))
00305742 Tomas Bortoli 2019-02-28 3988 break;
00305742 Tomas Bortoli 2019-02-28 3989
a9de9248 Marcel Holtmann 2007-10-20 3990 bacpy(&data.bdaddr, &info->bdaddr);
a9de9248 Marcel Holtmann 2007-10-20 3991 data.pscan_rep_mode = info->pscan_rep_mode;
a9de9248 Marcel Holtmann 2007-10-20 3992 data.pscan_period_mode = info->pscan_period_mode;
a9de9248 Marcel Holtmann 2007-10-20 3993 data.pscan_mode = info->pscan_mode;
a9de9248 Marcel Holtmann 2007-10-20 3994 memcpy(data.dev_class, info->dev_class, 3);
a9de9248 Marcel Holtmann 2007-10-20 3995 data.clock_offset = info->clock_offset;
a9de9248 Marcel Holtmann 2007-10-20 3996 data.rssi = info->rssi;
41a96212 Marcel Holtmann 2008-07-14 3997 data.ssp_mode = 0x00;
3175405b Johan Hedberg 2012-01-04 3998
regards,
dan carpenter
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] net/bluetooth: Fix bound check in event handling
2019-03-04 15:04 ` Dan Carpenter
@ 2019-03-04 19:58 ` Tomas Bortoli
0 siblings, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-04 19:58 UTC (permalink / raw)
To: Dan Carpenter, kbuild
Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth, netdev,
linux-kernel, syzkaller
Hi Dan,
On 3/4/19 4:04 PM, Dan Carpenter wrote:
> Hi Tomas,
>
> url: https://github.com/0day-ci/linux/commits/Tomas-Bortoli/net-bluetooth-Fix-bound-check-in-event-handling/20190301-213647
> base: https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master
>
> smatch warnings:
> net/bluetooth/hci_event.c:3986 hci_inquiry_result_with_rssi_evt() warn: potential pointer math issue ('info' is a 120 bit pointer)
>
> # https://github.com/0day-ci/linux/commit/00305742c021794f147b348d45eb10ea26e5a514
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout 00305742c021794f147b348d45eb10ea26e5a514
> vim +3986 net/bluetooth/hci_event.c
>
> a9de9248 Marcel Holtmann 2007-10-20 3979 if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
> 138d22ef Szymon Janc 2011-02-17 3980 struct inquiry_info_with_rssi_and_pscan_mode *info;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> 138d22ef Szymon Janc 2011-02-17 3981 info = (void *) (skb->data + 1);
> a9de9248 Marcel Holtmann 2007-10-20 3982
> e17acd40 Johan Hedberg 2011-03-30 3983 for (; num_rsp; num_rsp--, info++) {
> af58925c Marcel Holtmann 2014-07-01 3984 u32 flags;
> af58925c Marcel Holtmann 2014-07-01 3985
> 00305742 Tomas Bortoli 2019-02-28 @3986 if ((void *)(info + sizeof(info)) >
> ^^^^^^^^^^^^^^^^^^^
> This is a pointer math bug. The options to fix it are:
>
> if ((void *)info + sizeof(info) >
Yes, also sizeof(info) should be sizeof(*info)..
>
> Or:
> if ((void *)(info + 1) >
>
>
> 00305742 Tomas Bortoli 2019-02-28 3987 (void *)(skb->data + skb->len))
> 00305742 Tomas Bortoli 2019-02-28 3988 break;
> 00305742 Tomas Bortoli 2019-02-28 3989
> a9de9248 Marcel Holtmann 2007-10-20 3990 bacpy(&data.bdaddr, &info->bdaddr);
> a9de9248 Marcel Holtmann 2007-10-20 3991 data.pscan_rep_mode = info->pscan_rep_mode;
> a9de9248 Marcel Holtmann 2007-10-20 3992 data.pscan_period_mode = info->pscan_period_mode;
> a9de9248 Marcel Holtmann 2007-10-20 3993 data.pscan_mode = info->pscan_mode;
> a9de9248 Marcel Holtmann 2007-10-20 3994 memcpy(data.dev_class, info->dev_class, 3);
> a9de9248 Marcel Holtmann 2007-10-20 3995 data.clock_offset = info->clock_offset;
> a9de9248 Marcel Holtmann 2007-10-20 3996 data.rssi = info->rssi;
> 41a96212 Marcel Holtmann 2008-07-14 3997 data.ssp_mode = 0x00;
> 3175405b Johan Hedberg 2012-01-04 3998
>
> regards,
> dan carpenter
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation
>
regards,
Tomas
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH] net/bluetooth: Fix bound check in event handling
2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
2019-03-02 16:46 ` Marcel Holtmann
2019-03-04 15:04 ` Dan Carpenter
@ 2019-03-04 20:20 ` Tomas Bortoli
2019-03-30 7:17 ` Dan Carpenter
3 siblings, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-04 20:20 UTC (permalink / raw)
To: marcel, johan.hedberg
Cc: davem, linux-bluetooth, netdev, linux-kernel, syzkaller,
Tomas Bortoli
hci_inquiry_result_with_rssi_evt() can perform out of bound reads
on skb->data as a bound check is missing.
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+cec7a50c412a2c03f8f5@syzkaller.appspotmail.com
Reported-by: syzbot+660883c56e2fa65d4497@syzkaller.appspotmail.com
---
v2:
- changed sizeof(info) into sizeof(*info), as it should be.
- simplified expression in if
net/bluetooth/hci_event.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ac2826ce162b..4cbad1e1a322 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3978,11 +3978,15 @@ static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
struct inquiry_info_with_rssi_and_pscan_mode *info;
+ void *data_end = (void *)skb->data + skb->len;
info = (void *) (skb->data + 1);
for (; num_rsp; num_rsp--, info++) {
u32 flags;
+ if ((void *)info + sizeof(*info) > data_end)
+ break;
+
bacpy(&data.bdaddr, &info->bdaddr);
data.pscan_rep_mode = info->pscan_rep_mode;
data.pscan_period_mode = info->pscan_period_mode;
--
2.11.0
^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH] net/bluetooth: Fix bound check in event handling
2019-02-28 19:59 [PATCH] net/bluetooth: Fix bound check in event handling Tomas Bortoli
` (2 preceding siblings ...)
2019-03-04 20:20 ` Tomas Bortoli
@ 2019-03-30 7:17 ` Dan Carpenter
2019-03-30 8:23 ` [kbuild] " Dan Carpenter
2019-03-30 22:37 ` Tomas Bortoli
3 siblings, 2 replies; 9+ messages in thread
From: Dan Carpenter @ 2019-03-30 7:17 UTC (permalink / raw)
To: kbuild, Tomas Bortoli
Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth, netdev,
linux-kernel, syzkaller, Tomas Bortoli
[ This is an old warning. Sorry for missing it earlier. I would have
caught it when the code was merged as well so there was no real risk
but it's just awkward. ]
Hi Tomas,
url: https://github.com/0day-ci/linux/commits/Tomas-Bortoli/net-bluetooth-Fix-bound-check-in-event-handling/20190301-213647
base: https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master
smatch warnings:
net/bluetooth/hci_event.c:3986 hci_inquiry_result_with_rssi_evt() warn: potential pointer math issue ('info' is a 120 bit pointer)
# https://github.com/0day-ci/linux/commit/00305742c021794f147b348d45eb10ea26e5a514
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 00305742c021794f147b348d45eb10ea26e5a514
vim +3986 net/bluetooth/hci_event.c
6039aa73 Gustavo Padovan 2012-05-23 3963 static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
807deac2 Gustavo Padovan 2012-05-17 3964 struct sk_buff *skb)
a9de9248 Marcel Holtmann 2007-10-20 3965 {
a9de9248 Marcel Holtmann 2007-10-20 3966 struct inquiry_data data;
a9de9248 Marcel Holtmann 2007-10-20 3967 int num_rsp = *((__u8 *) skb->data);
a9de9248 Marcel Holtmann 2007-10-20 3968
a9de9248 Marcel Holtmann 2007-10-20 3969 BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
a9de9248 Marcel Holtmann 2007-10-20 3970
a9de9248 Marcel Holtmann 2007-10-20 3971 if (!num_rsp)
a9de9248 Marcel Holtmann 2007-10-20 3972 return;
a9de9248 Marcel Holtmann 2007-10-20 3973
d7a5a11d Marcel Holtmann 2015-03-13 3974 if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
1519cc17 Andre Guedes 2012-03-21 3975 return;
1519cc17 Andre Guedes 2012-03-21 3976
a9de9248 Marcel Holtmann 2007-10-20 3977 hci_dev_lock(hdev);
a9de9248 Marcel Holtmann 2007-10-20 3978
a9de9248 Marcel Holtmann 2007-10-20 3979 if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
138d22ef Szymon Janc 2011-02-17 3980 struct inquiry_info_with_rssi_and_pscan_mode *info;
138d22ef Szymon Janc 2011-02-17 3981 info = (void *) (skb->data + 1);
a9de9248 Marcel Holtmann 2007-10-20 3982
e17acd40 Johan Hedberg 2011-03-30 3983 for (; num_rsp; num_rsp--, info++) {
af58925c Marcel Holtmann 2014-07-01 3984 u32 flags;
af58925c Marcel Holtmann 2014-07-01 3985
00305742 Tomas Bortoli 2019-02-28 @3986 if ((void *)(info + sizeof(info)) >
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This should be (void *)info + sizeof(info). The code you have will
break for valid uses because the pointer math error. I notice that
this isn't merged into linux-next, but it does seem required. I am
writing a similar fix for a different function.
Another way to write this would be:
if ((u8 *)(info + 1) > &skb->data[skb->len]) {
00305742 Tomas Bortoli 2019-02-28 3987 (void *)(skb->data + skb->len))
00305742 Tomas Bortoli 2019-02-28 3988 break;
00305742 Tomas Bortoli 2019-02-28 3989
a9de9248 Marcel Holtmann 2007-10-20 3990 bacpy(&data.bdaddr, &info->bdaddr);
a9de9248 Marcel Holtmann 2007-10-20 3991 data.pscan_rep_mode = info->pscan_rep_mode;
a9de9248 Marcel Holtmann 2007-10-20 3992 data.pscan_period_mode = info->pscan_period_mode;
a9de9248 Marcel Holtmann 2007-10-20 3993 data.pscan_mode = info->pscan_mode;
a9de9248 Marcel Holtmann 2007-10-20 3994 memcpy(data.dev_class, info->dev_class, 3);
a9de9248 Marcel Holtmann 2007-10-20 3995 data.clock_offset = info->clock_offset;
a9de9248 Marcel Holtmann 2007-10-20 3996 data.rssi = info->rssi;
41a96212 Marcel Holtmann 2008-07-14 3997 data.ssp_mode = 0x00;
3175405b Johan Hedberg 2012-01-04 3998
af58925c Marcel Holtmann 2014-07-01 3999 flags = hci_inquiry_cache_update(hdev, &data, false);
af58925c Marcel Holtmann 2014-07-01 4000
48264f06 Johan Hedberg 2011-11-09 4001 mgmt_device_found(hdev, &info->bdaddr, ACL_LINK, 0x00,
e17acd40 Johan Hedberg 2011-03-30 4002 info->dev_class, info->rssi,
af58925c Marcel Holtmann 2014-07-01 4003 flags, NULL, 0, NULL, 0);
a9de9248 Marcel Holtmann 2007-10-20 4004 }
a9de9248 Marcel Holtmann 2007-10-20 4005 } else {
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [kbuild] [PATCH] net/bluetooth: Fix bound check in event handling
2019-03-30 7:17 ` Dan Carpenter
@ 2019-03-30 8:23 ` Dan Carpenter
2019-03-30 22:37 ` Tomas Bortoli
1 sibling, 0 replies; 9+ messages in thread
From: Dan Carpenter @ 2019-03-30 8:23 UTC (permalink / raw)
To: kbuild, Tomas Bortoli
Cc: johan.hedberg, netdev, marcel, linux-kernel, linux-bluetooth,
syzkaller, kbuild-all, davem
On Sat, Mar 30, 2019 at 10:17:57AM +0300, Dan Carpenter wrote:
> [ This is an old warning. Sorry for missing it earlier. I would have
> caught it when the code was merged as well so there was no real risk
> but it's just awkward. ]
>
> Hi Tomas,
>
> url: https://github.com/0day-ci/linux/commits/Tomas-Bortoli/net-bluetooth-Fix-bound-check-in-event-handling/20190301-213647
> base: https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master
>
> smatch warnings:
> net/bluetooth/hci_event.c:3986 hci_inquiry_result_with_rssi_evt() warn: potential pointer math issue ('info' is a 120 bit pointer)
>
> # https://github.com/0day-ci/linux/commit/00305742c021794f147b348d45eb10ea26e5a514
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout 00305742c021794f147b348d45eb10ea26e5a514
> vim +3986 net/bluetooth/hci_event.c
>
> 6039aa73 Gustavo Padovan 2012-05-23 3963 static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
> 807deac2 Gustavo Padovan 2012-05-17 3964 struct sk_buff *skb)
> a9de9248 Marcel Holtmann 2007-10-20 3965 {
> a9de9248 Marcel Holtmann 2007-10-20 3966 struct inquiry_data data;
> a9de9248 Marcel Holtmann 2007-10-20 3967 int num_rsp = *((__u8 *) skb->data);
> a9de9248 Marcel Holtmann 2007-10-20 3968
> a9de9248 Marcel Holtmann 2007-10-20 3969 BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
> a9de9248 Marcel Holtmann 2007-10-20 3970
> a9de9248 Marcel Holtmann 2007-10-20 3971 if (!num_rsp)
> a9de9248 Marcel Holtmann 2007-10-20 3972 return;
> a9de9248 Marcel Holtmann 2007-10-20 3973
> d7a5a11d Marcel Holtmann 2015-03-13 3974 if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
> 1519cc17 Andre Guedes 2012-03-21 3975 return;
> 1519cc17 Andre Guedes 2012-03-21 3976
> a9de9248 Marcel Holtmann 2007-10-20 3977 hci_dev_lock(hdev);
> a9de9248 Marcel Holtmann 2007-10-20 3978
> a9de9248 Marcel Holtmann 2007-10-20 3979 if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
> 138d22ef Szymon Janc 2011-02-17 3980 struct inquiry_info_with_rssi_and_pscan_mode *info;
> 138d22ef Szymon Janc 2011-02-17 3981 info = (void *) (skb->data + 1);
> a9de9248 Marcel Holtmann 2007-10-20 3982
> e17acd40 Johan Hedberg 2011-03-30 3983 for (; num_rsp; num_rsp--, info++) {
> af58925c Marcel Holtmann 2014-07-01 3984 u32 flags;
> af58925c Marcel Holtmann 2014-07-01 3985
> 00305742 Tomas Bortoli 2019-02-28 @3986 if ((void *)(info + sizeof(info)) >
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This should be (void *)info + sizeof(info). The code you have will
^^^^^^^^^^^^
sizeof(*info)
Sorry...
regards,
dan carpenter
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH] net/bluetooth: Fix bound check in event handling
2019-03-30 7:17 ` Dan Carpenter
2019-03-30 8:23 ` [kbuild] " Dan Carpenter
@ 2019-03-30 22:37 ` Tomas Bortoli
1 sibling, 0 replies; 9+ messages in thread
From: Tomas Bortoli @ 2019-03-30 22:37 UTC (permalink / raw)
To: Dan Carpenter, kbuild
Cc: kbuild-all, marcel, johan.hedberg, davem, linux-bluetooth, netdev,
linux-kernel, syzkaller
Hi Dan,
On 3/30/19 8:17 AM, Dan Carpenter wrote:
> [ This is an old warning. Sorry for missing it earlier. I would have
> caught it when the code was merged as well so there was no real risk
> but it's just awkward. ]
>
> Hi Tomas,
>
> url: https://github.com/0day-ci/linux/commits/Tomas-Bortoli/net-bluetooth-Fix-bound-check-in-event-handling/20190301-213647
> base: https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git master
>
> smatch warnings:
> net/bluetooth/hci_event.c:3986 hci_inquiry_result_with_rssi_evt() warn: potential pointer math issue ('info' is a 120 bit pointer)
>
> # https://github.com/0day-ci/linux/commit/00305742c021794f147b348d45eb10ea26e5a514
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout 00305742c021794f147b348d45eb10ea26e5a514
> vim +3986 net/bluetooth/hci_event.c
>
> 6039aa73 Gustavo Padovan 2012-05-23 3963 static void hci_inquiry_result_with_rssi_evt(struct hci_dev *hdev,
> 807deac2 Gustavo Padovan 2012-05-17 3964 struct sk_buff *skb)
> a9de9248 Marcel Holtmann 2007-10-20 3965 {
> a9de9248 Marcel Holtmann 2007-10-20 3966 struct inquiry_data data;
> a9de9248 Marcel Holtmann 2007-10-20 3967 int num_rsp = *((__u8 *) skb->data);
> a9de9248 Marcel Holtmann 2007-10-20 3968
> a9de9248 Marcel Holtmann 2007-10-20 3969 BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
> a9de9248 Marcel Holtmann 2007-10-20 3970
> a9de9248 Marcel Holtmann 2007-10-20 3971 if (!num_rsp)
> a9de9248 Marcel Holtmann 2007-10-20 3972 return;
> a9de9248 Marcel Holtmann 2007-10-20 3973
> d7a5a11d Marcel Holtmann 2015-03-13 3974 if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
> 1519cc17 Andre Guedes 2012-03-21 3975 return;
> 1519cc17 Andre Guedes 2012-03-21 3976
> a9de9248 Marcel Holtmann 2007-10-20 3977 hci_dev_lock(hdev);
> a9de9248 Marcel Holtmann 2007-10-20 3978
> a9de9248 Marcel Holtmann 2007-10-20 3979 if ((skb->len - 1) / num_rsp != sizeof(struct inquiry_info_with_rssi)) {
> 138d22ef Szymon Janc 2011-02-17 3980 struct inquiry_info_with_rssi_and_pscan_mode *info;
> 138d22ef Szymon Janc 2011-02-17 3981 info = (void *) (skb->data + 1);
> a9de9248 Marcel Holtmann 2007-10-20 3982
> e17acd40 Johan Hedberg 2011-03-30 3983 for (; num_rsp; num_rsp--, info++) {
> af58925c Marcel Holtmann 2014-07-01 3984 u32 flags;
> af58925c Marcel Holtmann 2014-07-01 3985
> 00305742 Tomas Bortoli 2019-02-28 @3986 if ((void *)(info + sizeof(info)) >
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This should be (void *)info + sizeof(info). The code you have will
> break for valid uses because the pointer math error. I notice that
> this isn't merged into linux-next, but it does seem required. I am
> writing a similar fix for a different function.
>
> Another way to write this would be:
>
> if ((u8 *)(info + 1) > &skb->data[skb->len]) {
Yeah it hasn't been accepted afaik. Why just + 1 ? Also,
&skb->data[skb->len] is right after the last byte so the > should rather
be a >=, I think.
your code looks better (as per pointer casting) but is logically
different from what I proposed with v2:
https://lkml.org/lkml/2019/3/4/892
I think the bound check should validate that there is enough data from
the info pointer to read an entire struct
inquiry_info_with_rssi_and_pscan_mode.
Best regards,
Tomas
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