Re: [PATCH for-rc 1/3] IB/hfi1: Validate fault injection opcode user input

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Jun 07, 2019 at 08:25:25AM -0400, Dennis Dalessandro wrote:
> From: Kaike Wan <kaike.wan@intel.com>
> 
> The opcode range for fault injection from user should be validated
> before it is applied to the fault->opcodes[] bitmap to avoid
> out-of-bound error. In addition, this patch also simplifies the code
> by using the BIT macro.
> 
> Fixes: a74d5307caba ("IB/hfi1: Rework fault injection machinery")
> Cc: <stable@vger.kernel.org>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
> Signed-off-by: Kaike Wan <kaike.wan@intel.com>
> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
>  drivers/infiniband/hw/hfi1/fault.c |    5 +++++
>  drivers/infiniband/hw/hfi1/fault.h |    6 +++---
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/fault.c b/drivers/infiniband/hw/hfi1/fault.c
> index 3fd3315..13ba291 100644
> +++ b/drivers/infiniband/hw/hfi1/fault.c
> @@ -153,6 +153,7 @@ static ssize_t fault_opcodes_write(struct file *file, const char __user *buf,
>  		char *dash;
>  		unsigned long range_start, range_end, i;
>  		bool remove = false;
> +		unsigned long bound = BIT(BITS_PER_BYTE);
>  
>  		end = strchr(ptr, ',');
>  		if (end)
> @@ -178,6 +179,10 @@ static ssize_t fault_opcodes_write(struct file *file, const char __user *buf,
>  				    BITS_PER_BYTE);
>  			break;
>  		}
> +		/* Check the inputs */
> +		if (range_start >= bound || range_end >= bound)
> +			break;
> +
>  		for (i = range_start; i <= range_end; i++) {
>  			if (remove)
>  				clear_bit(i, fault->opcodes);
> diff --git a/drivers/infiniband/hw/hfi1/fault.h b/drivers/infiniband/hw/hfi1/fault.h
> index a833827..c61035c 100644
> +++ b/drivers/infiniband/hw/hfi1/fault.h
> @@ -60,13 +60,13 @@
>  struct fault {
>  	struct fault_attr attr;
>  	struct dentry *dir;
> -	u64 n_rxfaults[(1U << BITS_PER_BYTE)];
> -	u64 n_txfaults[(1U << BITS_PER_BYTE)];
> +	u64 n_rxfaults[BIT(BITS_PER_BYTE)];
> +	u64 n_txfaults[BIT(BITS_PER_BYTE)];
>  	u64 fault_skip;
>  	u64 skip;
>  	u64 fault_skip_usec;
>  	unsigned long skip_usec;
> -	unsigned long opcodes[(1U << BITS_PER_BYTE) / BITS_PER_LONG];
> +	unsigned long opcodes[BIT(BITS_PER_BYTE) / BITS_PER_LONG];
>  	bool enable;
>  	bool suppress_err;
>  	bool opcode;

I don't think this is a simplification, BIT() is intended to create
flag values, and this is an array length. I also wonder if
1<<BITS_PER_BYTE is really a sane constant to be using for something
that looks HW specific, and if opcodes is really wanting to be a
bitmap type..

So, I dropped this hunk.

Jason