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Commit 6722e78c authored by Philippe De Muyter's avatar Philippe De Muyter Committed by David S. Miller
Browse files

[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: default avatarPhilippe De Muyter <phdm@macqel.be>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dc8103f2

drivers/net/ppp_async.c

+14 −3
Original line number Diff line number Diff line
@@ -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 @@ 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, const unsigned char *buf, 
				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 */