Messages in this thread | | | Date | Wed, 12 Jul 2023 08:11:41 +0200 | Subject | Re: [PATCH v3] Bluetooth: btmtk: Fix null pointer when processing coredump | From | Paul Menzel <> |
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Dear Chris,
Am 12.07.23 um 07:18 schrieb Chris Lu: > There may be a potential null pointer risk if offset value is > less than 0 when doing memcmp in btmtk_process_coredump(). > Checking offset is valid before doing memcmp.
Use imperative mood: Check offset …
> Signed-off-by: Chris Lu <chris.lu@mediatek.com> > Co-developed-by: Sean Wang <sean.wang@mediatek.com> > Signed-off-by: Sean Wang <sean.wang@mediatek.com> > --- > v2: fix typo > v3: fix bot checking error > --- > drivers/bluetooth/btmtk.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c > index 786f775196ae..0f290430ae0e 100644 > --- a/drivers/bluetooth/btmtk.c > +++ b/drivers/bluetooth/btmtk.c > @@ -370,7 +370,7 @@ EXPORT_SYMBOL_GPL(btmtk_register_coredump); > int btmtk_process_coredump(struct hci_dev *hdev, struct sk_buff *skb) > { > struct btmediatek_data *data = hci_get_priv(hdev); > - int err; > + int err, offset; > > if (!IS_ENABLED(CONFIG_DEV_COREDUMP)) > return 0; > @@ -392,15 +392,15 @@ int btmtk_process_coredump(struct hci_dev *hdev, struct sk_buff *skb) > if (err < 0) > break; > data->cd_info.cnt++; > + offset = skb->len - sizeof(MTK_COREDUMP_END);
For `sizeof()` shouldn’t you use `size_t`? But that is unsigned of course. Maybe ssize_t then?
> > /* Mediatek coredump data would be more than MTK_COREDUMP_NUM */ > - if (data->cd_info.cnt > MTK_COREDUMP_NUM && > - skb->len > sizeof(MTK_COREDUMP_END) && > - !memcmp((char *)&skb->data[skb->len - sizeof(MTK_COREDUMP_END)], > - MTK_COREDUMP_END, sizeof(MTK_COREDUMP_END) - 1)) { > - bt_dev_info(hdev, "Mediatek coredump end"); > - hci_devcd_complete(hdev); > - } > + if (data->cd_info.cnt > MTK_COREDUMP_NUM && offset > 0)
Why not keep it like before, and just add the condition `skb->len < sizeof(MTK_COREDUMP_END)`? The compiler is probably going to optimize so the value is not calculated twice.
Kind regards,
Paul
> + if (!memcmp((char *)&skb->data[offset], MTK_COREDUMP_END, > + sizeof(MTK_COREDUMP_END) - 1)) { > + bt_dev_info(hdev, "Mediatek coredump end"); > + hci_devcd_complete(hdev); > + } > > break; > }
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