drivers/bluetooth/btmtk.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
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.
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);
/* 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)
+ 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;
}
--
2.18.0
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; > }
On Wed, 2023-07-12 at 08:11 +0200, Paul Menzel wrote: > > External email : Please do not click links or open attachments until > you have verified the sender or the content. > Dear Chris, > Dear Paul, Thanks for your review and feedback to Mediatek's Bluetooth driver code. > > 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? > yes, it's better to use ssize_t or size_t, I'll change declaratins of offset from int to ssize_t. > > > > /* 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 > > The reason why I send this patch is when I backport devcoredump feature to specific project with older kernel version, the compiler might not so optimized that it would cause kernel panic when run into memcmp. As a result, make sure `skb->len > sizeof(MTK_COREDUMP_END) ` before doing memcmp part can avoid null pointer issue. Besides, only in condition 'data->cd_info.cnt > MTK_COREDUMP_NUM && offset > 0' need to do memcmp to check the end of coredump. Driver do noting with condition `skb->len < sizeof(MTK_COREDUMP_END) ` that additional condiction is not really necessary. > > +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; > > }
Dear Chris, Am 12.07.23 um 10:53 schrieb Chris Lu (陸稚泓): > On Wed, 2023-07-12 at 08:11 +0200, Paul Menzel wrote: >> >> External email : Please do not click links or open attachments until >> you have verified the sender or the content. (It’d be nice if you removed such (automatically added) phrases from your reply.) > Thanks for your review and feedback to Mediatek's Bluetooth driver > code. Thank you for your reply. >> 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? > > yes, it's better to use ssize_t or size_t, I'll change declaratins of > offset from int to ssize_t. > >>> >>> /* 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. > The reason why I send this patch is when I backport devcoredump feature > to specific project with older kernel version, the compiler might not > so optimized that it would cause kernel panic when run into memcmp. > As a result, make sure `skb->len > sizeof(MTK_COREDUMP_END) ` before > doing memcmp part can avoid null pointer issue. > Besides, only in condition 'data->cd_info.cnt > MTK_COREDUMP_NUM && > offset > 0' need to do memcmp to check the end of coredump. Driver do > noting with condition `skb->len < sizeof(MTK_COREDUMP_END) ` that > additional condiction is not really necessary. Just to avoid misunderstandings, my point, to add the comparison and get rid of the variable `offset`. 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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