On Fri, Jan 13, 2012 at 11:35:42AM +0100, Eric Dumazet wrote: > Le vendredi 13 janvier 2012 à 18:08 +1100, Herbert Xu a écrit : > > On Fri, Jan 13, 2012 at 02:55:14AM +0300, Alexey Dobriyan wrote: > > > > > > Herbert, I couldn't come up with a single scenario. :-( > > > But the bug is easy to reproduce. > > > > OK, does this patch work for you? > > > > commit 31f4e55c09c1170f8b813c14b1299b70f50db414 > > Author: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > > Date: Fri Jan 13 18:06:50 2012 +1100 > > > > crypto: sha512 - Fix msg_schedule race > > > > The percpu msg_schedule setup was unsafe as a user in a process > > context can be interrupted by a softirq user which would then > > scribble over the exact same work area. This was discovered by > > Steffen Klassert. > > > > This patch based on ideas from Eric Dumazet fixes this by using > > two independent work areas. > > > > Reported-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> > > Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > > > > I wonder ... > > With 4096 cpus, do we really want to reserve 5242880 bytes of memory for > this function ? > > What about following patch instead ? > > (Trying a dynamic memory allocation, and fallback on a single > pre-allocated bloc of memory, shared by all cpus, protected by a > spinlock) If we want to do dynamic memory allocation, we could place it to the shash_desc context where we already store the intermediate digest value. This is preallocated anyway, so we don't need to do another allocation. -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
