From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiggers3@gmail.com (Eric Biggers) Date: Fri, 21 Apr 2017 11:34:45 -0700 Subject: [PATCH 2/5] KEYS: user_defined: sanitize key payloads In-Reply-To: <20091.1492783037@warthog.procyon.org.uk> References: <20170421083037.12746-3-ebiggers3@gmail.com> <20170421083037.12746-1-ebiggers3@gmail.com> <20091.1492783037@warthog.procyon.org.uk> Message-ID: <20170421183445.GB12755@gmail.com> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Fri, Apr 21, 2017 at 02:57:17PM +0100, David Howells wrote: > Eric Biggers wrote: > > > - kfree_rcu(zap, rcu); > > + call_rcu(&zap->rcu, user_free_payload_rcu); > > Add kzfree_rcu()? > > David We could, but it's not trivial because the way kfree_rcu() works is to store the offset of the rcu_head as the callback function, then have a special case in RCU reclaim that recognizes "function pointers" with value < 4096 and call kfree() rather than the function. To support kzfree_rcu() we'd need to reserve another 4096 bytes of the address space (maybe at the end?), then check for the special kzfree value on every RCU reclaim. Or equivalently it could be a flag. It's possible, but it may be best to just use a custom callback for now. Then if it can be shown later that there are a lot of users who would like a "kzfree_rcu()", it can be added. - Eric -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info@ http://vger.kernel.org/majordomo-info.html