| Message ID | 20231012-strncpy-drivers-net-ethernet-wangxun-txgbe-txgbe_main-c-v1-1-c9bb3270ac98@google.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: txgbe: replace deprecated strncpy with strscpy | expand |
On Thu, Oct 12, 2023 at 09:20:04PM +0000, Justin Stitt wrote: > strncpy() is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > Based on usage part_str usage within txgbe_read_pba_string(), we expect > part_str to be NUL-terminated but not necessarily NUL-padded: > | /* put a null character on the end of our string */ > | pba_num[10] = '\0'; > > Interestingly, part_str is not used after txgbe_read_pba_string(): > | ... > | err = txgbe_read_pba_string(wx, part_str, TXGBE_PBANUM_LENGTH); > | if (err) > | strscpy(part_str, "Unknown", sizeof(part_str)); > | > | netif_info(wx, probe, netdev, "%pM\n", netdev->dev_addr); > | > | return 0; > | > |err_remove_phy: > | txgbe_remove_phy(txgbe); > |err_release_hw: > | wx_clear_interrupt_scheme(wx); > | wx_control_hw(wx, false); > |err_free_mac_table: > | kfree(wx->mac_table); > |err_pci_release_regions: > | pci_release_selected_regions(pdev, > | pci_select_bars(pdev, IORESOURCE_MEM)); > |err_pci_disable_dev: > | pci_disable_device(pdev); > | return err; > |} > ... this means this strncpy (or now strscpy) is probably useless. For > now, let's make the swap to strscpy() as I am not sure if this is truly > dead code or not. Hi Julian I agree, this looks like dead code. Jiawen, please could you submit a patch cleaning this up. Either swap to strscpy() and make use of the string, or delete it all. Andrew --- pw-bot: cr
On Sunday, October 15, 2023 12:31 AM, Andrew Lunn wrote: > On Thu, Oct 12, 2023 at 09:20:04PM +0000, Justin Stitt wrote: > > strncpy() is deprecated for use on NUL-terminated destination strings > > [1] and as such we should prefer more robust and less ambiguous string > > interfaces. > > > > Based on usage part_str usage within txgbe_read_pba_string(), we expect > > part_str to be NUL-terminated but not necessarily NUL-padded: > > | /* put a null character on the end of our string */ > > | pba_num[10] = '\0'; > > > > Interestingly, part_str is not used after txgbe_read_pba_string(): > > | ... > > | err = txgbe_read_pba_string(wx, part_str, TXGBE_PBANUM_LENGTH); > > | if (err) > > | strscpy(part_str, "Unknown", sizeof(part_str)); > > | > > | netif_info(wx, probe, netdev, "%pM\n", netdev->dev_addr); > > | > > | return 0; > > | > > |err_remove_phy: > > | txgbe_remove_phy(txgbe); > > |err_release_hw: > > | wx_clear_interrupt_scheme(wx); > > | wx_control_hw(wx, false); > > |err_free_mac_table: > > | kfree(wx->mac_table); > > |err_pci_release_regions: > > | pci_release_selected_regions(pdev, > > | pci_select_bars(pdev, IORESOURCE_MEM)); > > |err_pci_disable_dev: > > | pci_disable_device(pdev); > > | return err; > > |} > > ... this means this strncpy (or now strscpy) is probably useless. For > > now, let's make the swap to strscpy() as I am not sure if this is truly > > dead code or not. > > Hi Julian > > I agree, this looks like dead code. > > Jiawen, please could you submit a patch cleaning this up. Either swap > to strscpy() and make use of the string, or delete it all. Ah, I think I missed a line to print this string. I'm going to add it.
diff --git a/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c b/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c index 5c3aed516ac2..c795fbab37be 100644 --- a/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c +++ b/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c @@ -739,7 +739,7 @@ static int txgbe_probe(struct pci_dev *pdev, /* First try to read PBA as a string */ err = txgbe_read_pba_string(wx, part_str, TXGBE_PBANUM_LENGTH); if (err) - strncpy(part_str, "Unknown", TXGBE_PBANUM_LENGTH); + strscpy(part_str, "Unknown", sizeof(part_str)); netif_info(wx, probe, netdev, "%pM\n", netdev->dev_addr);
strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. Based on usage part_str usage within txgbe_read_pba_string(), we expect part_str to be NUL-terminated but not necessarily NUL-padded: | /* put a null character on the end of our string */ | pba_num[10] = '\0'; Interestingly, part_str is not used after txgbe_read_pba_string(): | ... | err = txgbe_read_pba_string(wx, part_str, TXGBE_PBANUM_LENGTH); | if (err) | strscpy(part_str, "Unknown", sizeof(part_str)); | | netif_info(wx, probe, netdev, "%pM\n", netdev->dev_addr); | | return 0; | |err_remove_phy: | txgbe_remove_phy(txgbe); |err_release_hw: | wx_clear_interrupt_scheme(wx); | wx_control_hw(wx, false); |err_free_mac_table: | kfree(wx->mac_table); |err_pci_release_regions: | pci_release_selected_regions(pdev, | pci_select_bars(pdev, IORESOURCE_MEM)); |err_pci_disable_dev: | pci_disable_device(pdev); | return err; |} ... this means this strncpy (or now strscpy) is probably useless. For now, let's make the swap to strscpy() as I am not sure if this is truly dead code or not. Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt <justinstitt@google.com> --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/net/ethernet/wangxun/txgbe/txgbe_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 change-id: 20231012-strncpy-drivers-net-ethernet-wangxun-txgbe-txgbe_main-c-05152bafac20 Best regards, -- Justin Stitt <justinstitt@google.com>