Since these strings are expected to be NUL-terminated and the buffers are exactly sized (in vnic_client_data_len()) with no padding, strncpy() can be safely replaced with strscpy() here, as strncpy() on NUL-terminated string is considered deprecated[1]. This has the side-effect of silencing a -Warray-bounds warning due to the compiler being confused about the vlcd incrementing:
In file included from ./include/linux/string.h:253, from ./include/linux/bitmap.h:10, from ./include/linux/cpumask.h:12, from ./include/linux/mm_types_task.h:14, from ./include/linux/mm_types.h:5, from ./include/linux/buildid.h:5, from ./include/linux/module.h:14, from drivers/net/ethernet/ibm/ibmvnic.c:35: In function '__fortify_strncpy', inlined from 'vnic_add_client_data' at drivers/net/ethernet/ibm/ibmvnic.c:3919:2: ./include/linux/fortify-string.h:39:30: warning: '__builtin_strncpy' offset 12 from the object at 'v lcd' is out of the bounds of referenced subobject 'name' with type 'char[]' at offset 12 [-Warray-bo unds] 39 | #define __underlying_strncpy __builtin_strncpy | ^ ./include/linux/fortify-string.h:51:9: note: in expansion of macro '__underlying_strncpy' 51 | return __underlying_strncpy(p, q, size); | ^~~~~~~~~~~~~~~~~~~~ drivers/net/ethernet/ibm/ibmvnic.c: In function 'vnic_add_client_data': drivers/net/ethernet/ibm/ibmvnic.c:3883:7: note: subobject 'name' declared here 3883 | char name[]; | ^~~~ [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings Cc: Dany Madden <d...@linux.ibm.com> Cc: Sukadev Bhattiprolu <suka...@linux.ibm.com> Cc: Thomas Falcon <tlfal...@linux.ibm.com> Cc: Michael Ellerman <m...@ellerman.id.au> Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> Cc: Paul Mackerras <pau...@samba.org> Cc: "David S. Miller" <da...@davemloft.net> Cc: Jakub Kicinski <k...@kernel.org> Cc: net...@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Kees Cook <keesc...@chromium.org> --- drivers/net/ethernet/ibm/ibmvnic.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c index 2d8804ebdf96..adb0d5ca9ff1 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.c +++ b/drivers/net/ethernet/ibm/ibmvnic.c @@ -3909,21 +3909,21 @@ static void vnic_add_client_data(struct ibmvnic_adapter *adapter, vlcd->type = 1; len = strlen(os_name) + 1; vlcd->len = cpu_to_be16(len); - strncpy(vlcd->name, os_name, len); + strscpy(vlcd->name, os_name, len); vlcd = (struct vnic_login_client_data *)(vlcd->name + len); /* Type 2 - LPAR name */ vlcd->type = 2; len = strlen(utsname()->nodename) + 1; vlcd->len = cpu_to_be16(len); - strncpy(vlcd->name, utsname()->nodename, len); + strscpy(vlcd->name, utsname()->nodename, len); vlcd = (struct vnic_login_client_data *)(vlcd->name + len); /* Type 3 - device name */ vlcd->type = 3; len = strlen(adapter->netdev->name) + 1; vlcd->len = cpu_to_be16(len); - strncpy(vlcd->name, adapter->netdev->name, len); + strscpy(vlcd->name, adapter->netdev->name, len); } static int send_login(struct ibmvnic_adapter *adapter) -- 2.30.2