| Message ID | 20220622065117.23210-1-hbh25y@gmail.com (mailing list archive) |
|---|---|
| State | Rejected |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | nfc: st21nfca: fix possible double free in st21nfca_im_recv_dep_res_cb() | expand |
On Wed, 2022-06-22 at 14:51 +0800, Hangyu Hua wrote: > nfc_tm_data_received will free skb internally when it fails. There is no > need to free skb in st21nfca_im_recv_dep_res_cb again. > > Fix this by setting skb to NULL when nfc_tm_data_received fails. > > Fixes: 1892bf844ea0 ("NFC: st21nfca: Adding P2P support to st21nfca in Initiator & Target mode") > Signed-off-by: Hangyu Hua <hbh25y@gmail.com> > --- > drivers/nfc/st21nfca/dep.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/nfc/st21nfca/dep.c b/drivers/nfc/st21nfca/dep.c > index 1ec651e31064..07ac5688011c 100644 > --- a/drivers/nfc/st21nfca/dep.c > +++ b/drivers/nfc/st21nfca/dep.c > @@ -594,7 +594,8 @@ static void st21nfca_im_recv_dep_res_cb(void *context, struct sk_buff *skb, > ST21NFCA_NFC_DEP_PFB_PNI(dep_res->pfb + 1); > size++; > skb_pull(skb, size); > - nfc_tm_data_received(info->hdev->ndev, skb); > + if (nfc_tm_data_received(info->hdev->ndev, skb)) > + skb = NULL; Note that 'skb' not used (nor freed) by this function after this point: the next 'break' statement refears to the inner switch, and land to the execution flow to the 'return' statement a few lines below. kfree_skb(skb) is never reached. Paolo
On 2022/6/23 17:42, Paolo Abeni wrote: > On Wed, 2022-06-22 at 14:51 +0800, Hangyu Hua wrote: >> nfc_tm_data_received will free skb internally when it fails. There is no >> need to free skb in st21nfca_im_recv_dep_res_cb again. >> >> Fix this by setting skb to NULL when nfc_tm_data_received fails. >> >> Fixes: 1892bf844ea0 ("NFC: st21nfca: Adding P2P support to st21nfca in Initiator & Target mode") >> Signed-off-by: Hangyu Hua <hbh25y@gmail.com> >> --- >> drivers/nfc/st21nfca/dep.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/nfc/st21nfca/dep.c b/drivers/nfc/st21nfca/dep.c >> index 1ec651e31064..07ac5688011c 100644 >> --- a/drivers/nfc/st21nfca/dep.c >> +++ b/drivers/nfc/st21nfca/dep.c >> @@ -594,7 +594,8 @@ static void st21nfca_im_recv_dep_res_cb(void *context, struct sk_buff *skb, >> ST21NFCA_NFC_DEP_PFB_PNI(dep_res->pfb + 1); >> size++; >> skb_pull(skb, size); >> - nfc_tm_data_received(info->hdev->ndev, skb); >> + if (nfc_tm_data_received(info->hdev->ndev, skb)) >> + skb = NULL; > > Note that 'skb' not used (nor freed) by this function after this point: > the next 'break' statement refears to the inner switch, and land to the > execution flow to the 'return' statement a few lines below. > kfree_skb(skb) is never reached. > > Paolo > My fault. I messed up two switch statements. I will be more careful next time. hangyu
diff --git a/drivers/nfc/st21nfca/dep.c b/drivers/nfc/st21nfca/dep.c index 1ec651e31064..07ac5688011c 100644 --- a/drivers/nfc/st21nfca/dep.c +++ b/drivers/nfc/st21nfca/dep.c @@ -594,7 +594,8 @@ static void st21nfca_im_recv_dep_res_cb(void *context, struct sk_buff *skb, ST21NFCA_NFC_DEP_PFB_PNI(dep_res->pfb + 1); size++; skb_pull(skb, size); - nfc_tm_data_received(info->hdev->ndev, skb); + if (nfc_tm_data_received(info->hdev->ndev, skb)) + skb = NULL; break; case ST21NFCA_NFC_DEP_PFB_SUPERVISOR_PDU: pr_err("Received a SUPERVISOR PDU\n");
nfc_tm_data_received will free skb internally when it fails. There is no need to free skb in st21nfca_im_recv_dep_res_cb again. Fix this by setting skb to NULL when nfc_tm_data_received fails. Fixes: 1892bf844ea0 ("NFC: st21nfca: Adding P2P support to st21nfca in Initiator & Target mode") Signed-off-by: Hangyu Hua <hbh25y@gmail.com> --- drivers/nfc/st21nfca/dep.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)