[lttng-dev] [PATCH v2 lttng-ust] Fix: Accept bytecode of length 65536 bytes

[Mathieu Desnoyers]

* Christian Babeux (christian.babeux at efficios.com) wrote:
> In order to support the filter bytecode maximum length (65536 bytes),
> the lttng_ust_filter_bytecode len field type must be able to
> hold more than a uint16_t. Change the field type to a uint32_t.
> 
> Also, since the relocation table is located at the end of the actual
> bytecode, the reloc_table_offset (reloc_offset in ust-abi) field must
> support offset values larger than 65535. Change the field type to a
> uint32_t. This change will allow support of relocation table appended
> to larger bytecode without breaking the ABI if the need arise in the
> future.
> 
> Both changes currently breaks the filter ABI, but this should be a
> reasonable compromise since the filtering feature has not been
> released yet.
> 
> Signed-off-by: Christian Babeux <christian.babeux at efficios.com>
> ---
>  include/lttng/ust-abi.h       | 4 ++--
>  include/ust-comm.h            | 4 ++--
>  liblttng-ust/lttng-ust-comm.c | 8 ++++++++
>  3 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/include/lttng/ust-abi.h b/include/lttng/ust-abi.h
> index 0489e89..91639a7 100644
> --- a/include/lttng/ust-abi.h
> +++ b/include/lttng/ust-abi.h
> @@ -174,8 +174,8 @@ struct lttng_ust_calibrate {
>  
>  #define FILTER_BYTECODE_MAX_LEN		65536
>  struct lttng_ust_filter_bytecode {
> -	uint16_t len;
> -	uint16_t reloc_offset;
> +	uint32_t len;
> +	uint32_t reloc_offset;
>  	char data[0];
>  };
>  
> diff --git a/include/ust-comm.h b/include/ust-comm.h
> index b09fcca..4a3e4ce 100644
> --- a/include/ust-comm.h
> +++ b/include/ust-comm.h
> @@ -132,8 +132,8 @@ struct ustcomm_ust_msg {
>  		struct lttng_ust_tracer_version version;
>  		struct lttng_ust_tracepoint_iter tracepoint;
>  		struct {
> -			uint16_t data_size;	/* following filter data */
> -			uint16_t reloc_offset;
> +			uint32_t data_size;	/* following filter data */
> +			uint32_t reloc_offset;
>  		} filter;
>  	} u;
>  };
> diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
> index 842876f..009dc02 100644
> --- a/liblttng-ust/lttng-ust-comm.c
> +++ b/liblttng-ust/lttng-ust-comm.c
> @@ -293,6 +293,14 @@ int handle_message(struct sock_info *sock_info,
>  			ret = -EINVAL;
>  			goto error;
>  		}
> +
> +		if (lum->u.filter.reloc_offset > lum->u.filter.data_size) {

if (lum->u.filter.reloc_offset > lum->u.filter.data_size - 1) {

?


> +			ERR("Filter reloc offset %u is not within data\n",
> +				lum->u.filter.reloc_offset);
> +			ret = -EINVAL;
> +			goto error;
> +		}
> +
>  		bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size);
>  		if (!bytecode) {
>  			ret = -ENOMEM;
> -- 
> 1.7.11.4
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com