* [PATCH] [v2] hinic: avoid gcc -Wrestrict warning
@ 2021-03-24 13:07 Arnd Bergmann
2021-03-24 13:29 ` Rasmus Villemoes
2021-03-25 1:10 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 4+ messages in thread
From: Arnd Bergmann @ 2021-03-24 13:07 UTC (permalink / raw)
To: Bin Luo, David S. Miller, Jakub Kicinski
Cc: Arnd Bergmann, Rasmus Villemoes, netdev, linux-kernel
From: Arnd Bergmann <arnd@arndb.de>
With extra warnings enabled, gcc complains that snprintf should not
take the same buffer as source and destination:
drivers/net/ethernet/huawei/hinic/hinic_ethtool.c: In function 'hinic_set_settings_to_hw':
drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:480:9: error: 'snprintf' argument 4 overlaps destination object 'set_link_str' [-Werror=restrict]
480 | err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
481 | "%sspeed %d ", set_link_str, speed);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:464:7: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
464 | char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
Rewrite this to avoid the nested sprintf and instead use separate
buffers, which is simpler.
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: rework according to feedback from Rasmus. This one could
easily avoid most of the pitfalls
---
.../net/ethernet/huawei/hinic/hinic_ethtool.c | 25 ++++++++-----------
1 file changed, 10 insertions(+), 15 deletions(-)
diff --git a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
index c340d9acba80..d7e20dab6e48 100644
--- a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
+++ b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
@@ -34,7 +34,7 @@
#include "hinic_rx.h"
#include "hinic_dev.h"
-#define SET_LINK_STR_MAX_LEN 128
+#define SET_LINK_STR_MAX_LEN 16
#define GET_SUPPORTED_MODE 0
#define GET_ADVERTISED_MODE 1
@@ -462,24 +462,19 @@ static int hinic_set_settings_to_hw(struct hinic_dev *nic_dev,
{
struct hinic_link_ksettings_info settings = {0};
char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
+ const char *autoneg_str;
struct net_device *netdev = nic_dev->netdev;
enum nic_speed_level speed_level = 0;
int err;
- err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN, "%s",
- (set_settings & HILINK_LINK_SET_AUTONEG) ?
- (autoneg ? "autong enable " : "autong disable ") : "");
- if (err < 0 || err >= SET_LINK_STR_MAX_LEN) {
- netif_err(nic_dev, drv, netdev, "Failed to snprintf link state, function return(%d) and dest_len(%d)\n",
- err, SET_LINK_STR_MAX_LEN);
- return -EFAULT;
- }
+ autoneg_str = (set_settings & HILINK_LINK_SET_AUTONEG) ?
+ (autoneg ? "autong enable " : "autong disable ") : "";
if (set_settings & HILINK_LINK_SET_SPEED) {
speed_level = hinic_ethtool_to_hw_speed_level(speed);
err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
- "%sspeed %d ", set_link_str, speed);
- if (err <= 0 || err >= SET_LINK_STR_MAX_LEN) {
+ "speed %d ", speed);
+ if (err >= SET_LINK_STR_MAX_LEN) {
netif_err(nic_dev, drv, netdev, "Failed to snprintf link speed, function return(%d) and dest_len(%d)\n",
err, SET_LINK_STR_MAX_LEN);
return -EFAULT;
@@ -494,11 +489,11 @@ static int hinic_set_settings_to_hw(struct hinic_dev *nic_dev,
err = hinic_set_link_settings(nic_dev->hwdev, &settings);
if (err != HINIC_MGMT_CMD_UNSUPPORTED) {
if (err)
- netif_err(nic_dev, drv, netdev, "Set %s failed\n",
- set_link_str);
+ netif_err(nic_dev, drv, netdev, "Set %s%sfailed\n",
+ autoneg_str, set_link_str);
else
- netif_info(nic_dev, drv, netdev, "Set %s successfully\n",
- set_link_str);
+ netif_info(nic_dev, drv, netdev, "Set %s%ssuccessfully\n",
+ autoneg_str, set_link_str);
return err;
}
--
2.29.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning
2021-03-24 13:07 [PATCH] [v2] hinic: avoid gcc -Wrestrict warning Arnd Bergmann
@ 2021-03-24 13:29 ` Rasmus Villemoes
2021-03-24 14:25 ` Arnd Bergmann
2021-03-25 1:10 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 4+ messages in thread
From: Rasmus Villemoes @ 2021-03-24 13:29 UTC (permalink / raw)
To: Arnd Bergmann, Bin Luo, David S. Miller, Jakub Kicinski
Cc: Arnd Bergmann, Rasmus Villemoes, netdev, linux-kernel
On 24/03/2021 14.07, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> With extra warnings enabled, gcc complains that snprintf should not
> take the same buffer as source and destination:
>
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c: In function 'hinic_set_settings_to_hw':
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:480:9: error: 'snprintf' argument 4 overlaps destination object 'set_link_str' [-Werror=restrict]
> 480 | err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 481 | "%sspeed %d ", set_link_str, speed);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:464:7: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
> 464 | char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
>
> Rewrite this to avoid the nested sprintf and instead use separate
> buffers, which is simpler.
>
This looks much better. Thanks.
> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: rework according to feedback from Rasmus. This one could
> easily avoid most of the pitfalls
> ---
> .../net/ethernet/huawei/hinic/hinic_ethtool.c | 25 ++++++++-----------
> 1 file changed, 10 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
> index c340d9acba80..d7e20dab6e48 100644
> --- a/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
> +++ b/drivers/net/ethernet/huawei/hinic/hinic_ethtool.c
> @@ -34,7 +34,7 @@
> #include "hinic_rx.h"
> #include "hinic_dev.h"
>
> -#define SET_LINK_STR_MAX_LEN 128
> +#define SET_LINK_STR_MAX_LEN 16
>
> #define GET_SUPPORTED_MODE 0
> #define GET_ADVERTISED_MODE 1
> @@ -462,24 +462,19 @@ static int hinic_set_settings_to_hw(struct hinic_dev *nic_dev,
> {
> struct hinic_link_ksettings_info settings = {0};
> char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
> + const char *autoneg_str;
> struct net_device *netdev = nic_dev->netdev;
> enum nic_speed_level speed_level = 0;
> int err;
>
> - err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN, "%s",
> - (set_settings & HILINK_LINK_SET_AUTONEG) ?
> - (autoneg ? "autong enable " : "autong disable ") : "");
> - if (err < 0 || err >= SET_LINK_STR_MAX_LEN) {
> - netif_err(nic_dev, drv, netdev, "Failed to snprintf link state, function return(%d) and dest_len(%d)\n",
> - err, SET_LINK_STR_MAX_LEN);
> - return -EFAULT;
> - }
> + autoneg_str = (set_settings & HILINK_LINK_SET_AUTONEG) ?
> + (autoneg ? "autong enable " : "autong disable ") : "";
>
> if (set_settings & HILINK_LINK_SET_SPEED) {
> speed_level = hinic_ethtool_to_hw_speed_level(speed);
> err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
> - "%sspeed %d ", set_link_str, speed);
> - if (err <= 0 || err >= SET_LINK_STR_MAX_LEN) {
> + "speed %d ", speed);
> + if (err >= SET_LINK_STR_MAX_LEN) {
> netif_err(nic_dev, drv, netdev, "Failed to snprintf link speed, function return(%d) and dest_len(%d)\n",
> err, SET_LINK_STR_MAX_LEN);
> return -EFAULT;
It's not your invention of course, but this both seems needlessly harsh
and EFAULT is a weird error to return. It's just a printk() message that
might be truncated, and now that the format string only has a %d
specifier, it can actually be verified statically that overflow will
never happen (though I don't know or think gcc can do that, perhaps
there's some locale nonsense in the standard that allows using
utf16-encoded sanskrit runes). So probably that test should just be
dropped, but that's a separate thing.
Reviewed-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning
2021-03-24 13:29 ` Rasmus Villemoes
@ 2021-03-24 14:25 ` Arnd Bergmann
0 siblings, 0 replies; 4+ messages in thread
From: Arnd Bergmann @ 2021-03-24 14:25 UTC (permalink / raw)
To: Rasmus Villemoes
Cc: Bin Luo, David S. Miller, Jakub Kicinski, Networking,
Linux Kernel Mailing List
On Wed, Mar 24, 2021 at 2:29 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
> On 24/03/2021 14.07, Arnd Bergmann wrote:
>
> > if (set_settings & HILINK_LINK_SET_SPEED) {
> > speed_level = hinic_ethtool_to_hw_speed_level(speed);
> > err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
> > - "%sspeed %d ", set_link_str, speed);
> > - if (err <= 0 || err >= SET_LINK_STR_MAX_LEN) {
> > + "speed %d ", speed);
> > + if (err >= SET_LINK_STR_MAX_LEN) {
> > netif_err(nic_dev, drv, netdev, "Failed to snprintf link speed, function return(%d) and dest_len(%d)\n",
> > err, SET_LINK_STR_MAX_LEN);
> > return -EFAULT;
>
> It's not your invention of course, but this both seems needlessly harsh
> and EFAULT is a weird error to return. It's just a printk() message that
> might be truncated, and now that the format string only has a %d
> specifier, it can actually be verified statically that overflow will
> never happen (though I don't know or think gcc can do that, perhaps
> there's some locale nonsense in the standard that allows using
> utf16-encoded sanskrit runes). So probably that test should just be
> dropped, but that's a separate thing.
I thought about fixing it, but this seemed to be a rabbit hole I didn't
want to get into, as there are other harmless issues in the driver
that could be improved.
I'm fairly sure gcc can indeed warn about the overflow with
-Wformat-truncation, but the warning is disabled at the moment
because it has a ton of false positives:
kernel/workqueue.c: In function 'create_worker':
kernel/workqueue.c:1933:55: error: '%d' directive output may be
truncated writing between 1 and 10 bytes into a region of size between
3 and 13 [-Werror=format-truncation=]
1933 | snprintf(id_buf, sizeof(id_buf), "u%d:%d",
pool->id, id);
Arnd
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] [v2] hinic: avoid gcc -Wrestrict warning
2021-03-24 13:07 [PATCH] [v2] hinic: avoid gcc -Wrestrict warning Arnd Bergmann
2021-03-24 13:29 ` Rasmus Villemoes
@ 2021-03-25 1:10 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-03-25 1:10 UTC (permalink / raw)
To: Arnd Bergmann; +Cc: luobin9, davem, kuba, arnd, linux, netdev, linux-kernel
Hello:
This patch was applied to netdev/net-next.git (refs/heads/master):
On Wed, 24 Mar 2021 14:07:22 +0100 you wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> With extra warnings enabled, gcc complains that snprintf should not
> take the same buffer as source and destination:
>
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c: In function 'hinic_set_settings_to_hw':
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:480:9: error: 'snprintf' argument 4 overlaps destination object 'set_link_str' [-Werror=restrict]
> 480 | err = snprintf(set_link_str, SET_LINK_STR_MAX_LEN,
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 481 | "%sspeed %d ", set_link_str, speed);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/net/ethernet/huawei/hinic/hinic_ethtool.c:464:7: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
> 464 | char set_link_str[SET_LINK_STR_MAX_LEN] = {0};
>
> [...]
Here is the summary with links:
- [v2] hinic: avoid gcc -Wrestrict warning
https://git.kernel.org/netdev/net-next/c/84c7f6c33f42
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-03-24 13:07 [PATCH] [v2] hinic: avoid gcc -Wrestrict warning Arnd Bergmann
2021-03-24 13:29 ` Rasmus Villemoes
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2021-03-25 1:10 ` patchwork-bot+netdevbpf
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