Re: [PATCH v1 2/5] ima-evm-utils: Fix possible strcpy overflow

[Mimi Zohar <zohar@linux.ibm.com>]

On Sat, 2019-07-13 at 00:28 +0300, Vitaly Chikunov wrote:
> caps_str is passed from command line but copied into fixed-size buffer.
> CID 229895.
> ---
>  src/evmctl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 39bc3d9..e07cff4 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -409,8 +409,9 @@ static int calc_evm_hash(const char *file, unsigned char *hash)
>  		} else if (!strcmp(*xattrname, XATTR_NAME_CAPS) && (hmac_flags & HMAC_FLAG_CAPS_SET)) {
>  			if (!caps_str)
>  				continue;
> -			strcpy(xattr_value, caps_str);
>  			err = strlen(caps_str);
> +			assert(err < sizeof(xattr_value));

"calc_evm_hash" can be called while walking and labeling, or
verifying, a file system.  We probably don't want to abruptly end it.
 Maybe emit an error message and return and error?


> +			strcpy(xattr_value, caps_str);
>  		} else {
>  			err = lgetxattr(file, *xattrname, xattr_value, sizeof(xattr_value));
>  			if (err < 0) {