| Message ID | 20241028080618.3540907-1-ruanjinjie@huawei.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: wwan: t7xx: off-by-one error in t7xx_dpmaif_rx_buf_alloc() | expand |
Hello Jinjie, On 28.10.2024 10:06, Jinjie Ruan wrote: > The error path in t7xx_dpmaif_rx_buf_alloc(), free and unmap the already > allocated and mapped skb in a loop, but the loop condition terminates when > the index reaches zero, which fails to free the first allocated skb at > index zero. > > Check for >= 0 so that skb at index 0 is freed as well. Nice catch! Still implementation needs some improvements, see below. > > Fixes: d642b012df70 ("net: wwan: t7xx: Add data path interface") > Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> > --- > drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > index 210d84c67ef9..f2298330e05b 100644 > --- a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > +++ b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > @@ -226,7 +226,7 @@ int t7xx_dpmaif_rx_buf_alloc(struct dpmaif_ctrl *dpmaif_ctrl, > return 0; > > err_unmap_skbs: > - while (--i > 0) > + while (--i >= 0) > t7xx_unmap_bat_skb(dpmaif_ctrl->dev, bat_req->bat_skb, i); The index variable declared as unsigned so changing the condition alone will cause the endless loop. Can you change the variable type to signed as well? -- Sergey
On Tue, 29 Oct 2024, Sergey Ryazanov wrote: > Hello Jinjie, > > On 28.10.2024 10:06, Jinjie Ruan wrote: > > The error path in t7xx_dpmaif_rx_buf_alloc(), free and unmap the already > > allocated and mapped skb in a loop, but the loop condition terminates when > > the index reaches zero, which fails to free the first allocated skb at > > index zero. > > > > Check for >= 0 so that skb at index 0 is freed as well. > > Nice catch! Still implementation needs some improvements, see below. > > > > > Fixes: d642b012df70 ("net: wwan: t7xx: Add data path interface") > > Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> > > --- > > drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > > b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > > index 210d84c67ef9..f2298330e05b 100644 > > --- a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > > +++ b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c > > @@ -226,7 +226,7 @@ int t7xx_dpmaif_rx_buf_alloc(struct dpmaif_ctrl > > *dpmaif_ctrl, > > return 0; > > err_unmap_skbs: > > - while (--i > 0) > > + while (--i >= 0) > > t7xx_unmap_bat_skb(dpmaif_ctrl->dev, bat_req->bat_skb, i); > > The index variable declared as unsigned so changing the condition alone will > cause the endless loop. Can you change the variable type to signed as well? Isn't the usual pattern: while (i--) t7xx_unmap_bat_skb(dpmaif_ctrl->dev, bat_req->bat_skb, i); ?
On October 29, 2024 12:52:39 PM, "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com> wrote: >On Tue, 29 Oct 2024, Sergey Ryazanov wrote: > >> Hello Jinjie, >> >> On 28.10.2024 10:06, Jinjie Ruan wrote: >>> The error path in t7xx_dpmaif_rx_buf_alloc(), free and unmap the already >>> allocated and mapped skb in a loop, but the loop condition terminates when >>> the index reaches zero, which fails to free the first allocated skb at >>> index zero. >>> >>> Check for >= 0 so that skb at index 0 is freed as well. >> >> Nice catch! Still implementation needs some improvements, see below. >> >>> >>> Fixes: d642b012df70 ("net: wwan: t7xx: Add data path interface") >>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> >>> --- >>> drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c >>> b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c >>> index 210d84c67ef9..f2298330e05b 100644 >>> --- a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c >>> +++ b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c >>> @@ -226,7 +226,7 @@ int t7xx_dpmaif_rx_buf_alloc(struct dpmaif_ctrl >>> *dpmaif_ctrl, >>> return 0; >>> err_unmap_skbs: >>> - while (--i > 0) >>> + while (--i >= 0) >>> t7xx_unmap_bat_skb(dpmaif_ctrl->dev, bat_req->bat_skb, i); >> >> The index variable declared as unsigned so changing the condition alone will >> cause the endless loop. Can you change the variable type to signed as well? > >Isn't the usual pattern: > > while (i--) > t7xx_unmap_bat_skb(dpmaif_ctrl->dev, bat_req->bat_skb, i); > >? I can't say it's a usual pattern, but yes, you are right and your solution will work even without signedness change. Jinjie have sent a V2 with int I. And since I assume that loop format a matter of taste, I am going to Ack it. If you think that it is not only matter of taste or Jinjie wants to follow the suggested approach then I will be happy to Ack a new patch with the different loop implementation. -- Sergey Hello Ilpo,
diff --git a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c index 210d84c67ef9..f2298330e05b 100644 --- a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c +++ b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c @@ -226,7 +226,7 @@ int t7xx_dpmaif_rx_buf_alloc(struct dpmaif_ctrl *dpmaif_ctrl, return 0; err_unmap_skbs: - while (--i > 0) + while (--i >= 0) t7xx_unmap_bat_skb(dpmaif_ctrl->dev, bat_req->bat_skb, i); return ret;
The error path in t7xx_dpmaif_rx_buf_alloc(), free and unmap the already allocated and mapped skb in a loop, but the loop condition terminates when the index reaches zero, which fails to free the first allocated skb at index zero. Check for >= 0 so that skb at index 0 is freed as well. Fixes: d642b012df70 ("net: wwan: t7xx: Add data path interface") Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)