From: "Philippe De Muyter" 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 Cc: "David S. Miller" Cc: Paul Mackerras Signed-off-by: Andrew Morton --- drivers/net/ppp_async.c | 17 ++++++++++++++--- 1 files changed, 14 insertions(+), 3 deletions(-) diff -puN drivers/net/ppp_async.c~ppp-handle-misaligned-accesses-2 drivers/net/ppp_async.c --- 25/drivers/net/ppp_async.c~ppp-handle-misaligned-accesses-2 Wed Aug 17 13:47:43 2005 +++ 25-akpm/drivers/net/ppp_async.c Wed Aug 17 13:48:59 2005 @@ -31,6 +31,7 @@ #include #include #include +#include #define PPP_VERSION "2.4.2" @@ -835,8 +836,11 @@ process_input_packet(struct asyncppp *ap 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 @@ ppp_async_input(struct asyncppp *ap, con 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 */ _