`strncpy` is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces.
`buf` is used in this context as a data buffer with 64 bytes of memory to be occupied by capi_manufakturer. We see the caller capi20_get_manufacturer() passes data.manufacturer as its `buf` argument which is then later passed over to user space. Due to this, let's keep the NUL-padding that strncpy provided by using strscpy_pad so as to not leak any stack data. | cdev->errcode = capi20_get_manufacturer(data.contr, data.manufacturer); | if (cdev->errcode) | return -EIO; | | if (copy_to_user(argp, data.manufacturer, | sizeof(data.manufacturer))) | return -EFAULT; Perhaps this would also be a good instance to use `strtomem_pad` for but in my testing the compiler was not able to determine the size of `buf` -- even with all the hints. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt <justinst...@google.com> --- Note: build-tested only. --- drivers/isdn/capi/kcapi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/isdn/capi/kcapi.c b/drivers/isdn/capi/kcapi.c index ae24848af233..136ba9fe55e0 100644 --- a/drivers/isdn/capi/kcapi.c +++ b/drivers/isdn/capi/kcapi.c @@ -732,7 +732,7 @@ u16 capi20_get_manufacturer(u32 contr, u8 buf[CAPI_MANUFACTURER_LEN]) u16 ret; if (contr == 0) { - strncpy(buf, capi_manufakturer, CAPI_MANUFACTURER_LEN); + strscpy_pad(buf, capi_manufakturer, CAPI_MANUFACTURER_LEN); return CAPI_NOERROR; } @@ -740,7 +740,7 @@ u16 capi20_get_manufacturer(u32 contr, u8 buf[CAPI_MANUFACTURER_LEN]) ctr = get_capi_ctr_by_nr(contr); if (ctr && ctr->state == CAPI_CTR_RUNNING) { - strncpy(buf, ctr->manu, CAPI_MANUFACTURER_LEN); + strscpy_pad(buf, ctr->manu, CAPI_MANUFACTURER_LEN); ret = CAPI_NOERROR; } else ret = CAPI_REGNOTINSTALLED; --- base-commit: 2cf0f715623872823a72e451243bbf555d10d032 change-id: 20230922-strncpy-drivers-isdn-capi-kcapi-c-516f17f59684 Best regards, -- Justin Stitt <justinst...@google.com>
