David S. Miller wrote :
> From: Andrew Morton <[email protected]>
> Date: Sun, 29 May 2005 19:52:45 -0700
>
> > > All these patches to PPP and friends are merely papering over the
> > > larger problem.
> >
> > It's not a thing we want to do in the general case, sure. But it's
> > reasonable to identify those bits of net code which the nommu people care
> > about and look to see if there's some sane workaround to get them going.
> >
> > Otherwise, things like PPP will simply unavailable to some architectures...
>
> Some time ago there was a proposal that would allow appropriate
> handling of these sorts of things.
>
> Accessors to packet headers would go through a macro, and this
> along with some other defines would allow an architecture to
> decide between two schemes:
>
> 1) Use normal loads and stores, let trap handler take care of
> unaligned cases.
> 2) Use something akin to get_unaligned(), no trap handler stuff.
>
> Sure, to make things faster we can do something like this PPP
> patch, but it needs lots of work, first of all you need to
> replace this:
>
> for ( ... )
> p[i-1] = p[i];
>
> stuff with a proper memmove() call.
>
Ok, here is a revised patch :
This patch avoids ppp-generated kernel crashes on machines where
unaligned accesses are forbidden.
Signed-off-by: Philippe De Muyter <[email protected]>
--- linux/drivers/net/ppp_async.c.orig 2005-06-01 10:46:58.000000000 +0200
+++ linux/drivers/net/ppp_async.c 2005-06-01 17:04:13.000000000 +0200
@@ -31,6 +31,7 @@
#include <linux/spinlock.h>
#include <linux/init.h>
#include <asm/uaccess.h>
+#include <asm/string.h>
#define PPP_VERSION "2.4.2"
@@ -816,7 +817,15 @@ process_input_packet(struct asyncppp *ap
proto = p[0];
if (proto & 1) {
/* protocol is compressed */
- skb_push(skb, 1)[0] = 0;
+ if ((unsigned long)skb->data & 1)
+ skb_push(skb, 1)[0] = 0;
+ else { /* Ditto, but realign the payload to 4-byte boundary */
+ short len = skb->len;
+
+ skb_put(skb, 3);
+ memmove(skb->data + 3, skb->data, len);
+ skb_pull(skb, 2)[0] = 0;
+ }
} else {
if (skb->len < 2)
goto err;
@@ -890,6 +899,12 @@ ppp_async_input(struct asyncppp *ap, con
if (skb == 0)
goto nomem;
/* Try to get the payload 4-byte aligned */
+ /* This should match the
+ ** PPP_ALLSTATIONS/PPP_UI/compressed tests
+ ** in process_input_packet,
+ ** but we do not have enough chars here and
+ ** now to test buf[1] and buf[2].
+ */
if (buf[0] != PPP_ALLSTATIONS)
skb_reserve(skb, 2 + (buf[0] & 1));
ap->rpkt = skb;
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
