Re: [dpdk-stable] [dpdk-dev] [PATCH] drivers: fix to replace strcat with strncat

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 14 Jan 2019 13:29:38 +0000
Ferruh Yigit <ferruh.yigit@intel.com> wrote:

> On 1/14/2019 6:04 AM, Chaitanya Babu Talluri wrote:
> > Strcat does not check the destination length and there might be
> > chances of string overflow so insted of strcat, strncat is used.
> > 
> > Fixes: 540a211084 ("bnx2x: driver core")
> > Fixes: e163c18a15 ("net/i40e: update ptype and pctype info")
> > Fixes: ef28aa96e5 ("net/nfp: support multiprocess")
> > Fixes: 6f4eec2565 ("test/crypto: enhance scheduler unit tests")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Chaitanya Babu Talluri <tallurix.chaitanya.babu@intel.com>  
> 
> <...>
> 
> > @@ -685,11 +687,11 @@ nfp_acquire_secondary_process_lock(struct nfp_pcie_user *desc)
> >  	 * driver is used because that implies root user.
> >  	 */
> >  	home_path = getenv("HOME");
> > -	lockfile = calloc(strlen(home_path) + strlen(lockname) + 1,
> > +	lockfile = calloc(LOCKFILE_HOME_PATH + strlen(lockname) + 1,
> >  			  sizeof(char));
> >  
> > -	strcat(lockfile, home_path);
> > -	strcat(lockfile, "/.lock_nfp_secondary");
> > +	strncat(lockfile, home_path, LOCKFILE_HOME_PATH);
> > +	strncat(lockfile, lockname, strlen(lockfile));  
> 
> I guess this need to be 'LOCKFILE_HOME_PATH - strlen(lockfile) - 1' instead.
> But also this can be implemented as 'snprintf()'
> 
> Since 'lockfile' allocated dynamically based on sizes of existing strings, using
> 'lockname' instead of "/.lock_nfp_secondary" will show that there won't be any
> overflow but tools still may be complaining about 'strcat' usage.
> 
> 

Why not use vasprintf() instead of doing manual construction?