[PPP]: handle misaligned accesses
From: "Philippe De Muyter" <phdm@macqel.be>
This patch avoids ppp-generated kernel crashes on machines where unaligned
accesses are forbidden (ie: m68000), by fixing ppp alignment setting for
reused skb's.
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ppp_async.c b/drivers/net/ppp_async.c
index 59e8183..400f652 100644
--- a/drivers/net/ppp_async.c
+++ b/drivers/net/ppp_async.c
@@ -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"
@@ -835,8 +836,11 @@
err:
/* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
ap->state = SC_PREV_ERROR;
- if (skb)
+ if (skb) {
+ /* make skb appear as freshly allocated */
skb_trim(skb, 0);
+ skb_reserve(skb, - skb_headroom(skb));
+ }
}
/* Called when the tty driver has data for us. Runs parallel with the
@@ -889,10 +893,17 @@
skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
if (skb == 0)
goto nomem;
- /* Try to get the payload 4-byte aligned */
+ ap->rpkt = skb;
+ }
+ if (skb->len == 0) {
+ /* 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 to test buf[1] and buf[2].
+ */
if (buf[0] != PPP_ALLSTATIONS)
skb_reserve(skb, 2 + (buf[0] & 1));
- ap->rpkt = skb;
}
if (n > skb_tailroom(skb)) {
/* packet overflowed MRU */
