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cba58fcbc4
`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 <justinstitt@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230922-strncpy-drivers-isdn-capi-kcapi-c-v1-1-55fcf8b075fb@google.com Signed-off-by: Kees Cook <keescook@chromium.org> |
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