| Message ID | 20210817103108.1160-1-paskripkin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Bluetooth: add timeout sanity check to hci_inquiry | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | warning | 1 maintainers not CCed: kuba@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 35 this patch: 35 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 18 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 35 this patch: 35 |
| netdev/header_inline | success | Link |
Hi Pavel, > Syzbot hit "task hung" bug in hci_req_sync(). The problem was in > unreasonable huge inquiry timeout passed from userspace. > Fix it by adding sanity check for timeout value and add constant to > hsi_sock.h to inform userspace, that hci_inquiry_req::length field has > maximum possible value. > > Since hci_inquiry() is the only user of hci_req_sync() with user > controlled timeout value, it makes sense to check timeout value in > hci_inquiry() and don't touch hci_req_sync(). > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Reported-and-tested-by: syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> > --- > > Hi, Bluetooth maintainers/reviewers! > > I believe, 60 seconds will be more than enough for inquiry request. I've > searched for examples on the internet and maximum ir.length I found was > 8. Maybe, we have users, which need more than 60 seconds... I look forward > to receiving your views on this value. > > --- > include/net/bluetooth/hci_sock.h | 1 + > net/bluetooth/hci_core.c | 5 +++++ > 2 files changed, 6 insertions(+) > > diff --git a/include/net/bluetooth/hci_sock.h b/include/net/bluetooth/hci_sock.h > index 9949870f7d78..1cd63d4da00b 100644 > --- a/include/net/bluetooth/hci_sock.h > +++ b/include/net/bluetooth/hci_sock.h > @@ -168,6 +168,7 @@ struct hci_inquiry_req { > __u16 dev_id; > __u16 flags; > __u8 lap[3]; > +#define HCI_INQUIRY_MAX_TIMEOUT 30 > __u8 length; > __u8 num_rsp; > }; > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c > index e1a545c8a69f..104babf67351 100644 > --- a/net/bluetooth/hci_core.c > +++ b/net/bluetooth/hci_core.c > @@ -1343,6 +1343,11 @@ int hci_inquiry(void __user *arg) > goto done; > } > /* Restrict maximum inquiry length to 60 seconds */ if (ir.length > 60) { .. } > + if (ir.length > HCI_INQUIRY_MAX_TIMEOUT) { > + err = -EINVAL; > + goto done; > + } > + I found this easier to read than adding anything define somewhere else. And since this is a legacy interface that is no longer used by bluetoothd, this should be fine. We will start to deprecate this eventually. And I prefer 1 minute max time here. Just to be safe. Regards Marcel
On 8/19/21 6:05 PM, Marcel Holtmann wrote: > Hi Pavel, > >> } >> > > /* Restrict maximum inquiry length to 60 seconds */ > if (ir.length > 60) { > .. > } > >> + if (ir.length > HCI_INQUIRY_MAX_TIMEOUT) { >> + err = -EINVAL; >> + goto done; >> + } >> + > > I found this easier to read than adding anything define somewhere else. And since this is a legacy interface that is no longer used by bluetoothd, this should be fine. We will start to deprecate this eventually. > > And I prefer 1 minute max time here. Just to be safe. > I thought, that user-space should be aware of maximum value, that's why I decided to add this define :) I didn't know, that this interface is legacy. Will fix in v2, thank you! With regards, Pavel Skripkin
diff --git a/include/net/bluetooth/hci_sock.h b/include/net/bluetooth/hci_sock.h index 9949870f7d78..1cd63d4da00b 100644 --- a/include/net/bluetooth/hci_sock.h +++ b/include/net/bluetooth/hci_sock.h @@ -168,6 +168,7 @@ struct hci_inquiry_req { __u16 dev_id; __u16 flags; __u8 lap[3]; +#define HCI_INQUIRY_MAX_TIMEOUT 30 __u8 length; __u8 num_rsp; }; diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index e1a545c8a69f..104babf67351 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -1343,6 +1343,11 @@ int hci_inquiry(void __user *arg) goto done; } + if (ir.length > HCI_INQUIRY_MAX_TIMEOUT) { + err = -EINVAL; + goto done; + } + hci_dev_lock(hdev); if (inquiry_cache_age(hdev) > INQUIRY_CACHE_AGE_MAX || inquiry_cache_empty(hdev) || ir.flags & IREQ_CACHE_FLUSH) {
Syzbot hit "task hung" bug in hci_req_sync(). The problem was in unreasonable huge inquiry timeout passed from userspace. Fix it by adding sanity check for timeout value and add constant to hsi_sock.h to inform userspace, that hci_inquiry_req::length field has maximum possible value. Since hci_inquiry() is the only user of hci_req_sync() with user controlled timeout value, it makes sense to check timeout value in hci_inquiry() and don't touch hci_req_sync(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-and-tested-by: syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- Hi, Bluetooth maintainers/reviewers! I believe, 60 seconds will be more than enough for inquiry request. I've searched for examples on the internet and maximum ir.length I found was 8. Maybe, we have users, which need more than 60 seconds... I look forward to receiving your views on this value. --- include/net/bluetooth/hci_sock.h | 1 + net/bluetooth/hci_core.c | 5 +++++ 2 files changed, 6 insertions(+)