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[PPP]: handle misaligned accesses

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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>
This commit is contained in:
Philippe De Muyter 2005-11-08 09:40:26 -08:00 committed by David S. Miller
parent dc8103f25f
commit 6722e78c90
1 changed files with 14 additions and 3 deletions
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17
drivers/net/ppp_async.c
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@ -31,6 +31,7 @@
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/init.h> #include <linux/init.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <asm/string.h>
#define PPP_VERSION "2.4.2" #define PPP_VERSION "2.4.2"
@ -835,8 +836,11 @@ process_input_packet(struct asyncppp *ap)
err: err:
/* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */ /* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
ap->state = SC_PREV_ERROR; ap->state = SC_PREV_ERROR;
if (skb) if (skb) {
/* make skb appear as freshly allocated */
skb_trim(skb, 0); skb_trim(skb, 0);
skb_reserve(skb, - skb_headroom(skb));
}
} }
/* Called when the tty driver has data for us. Runs parallel with the /* 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); skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
if (skb == 0) if (skb == 0)
goto nomem; 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) if (buf[0] != PPP_ALLSTATIONS)
skb_reserve(skb, 2 + (buf[0] & 1)); skb_reserve(skb, 2 + (buf[0] & 1));
ap->rpkt = skb;
} }
if (n > skb_tailroom(skb)) { if (n > skb_tailroom(skb)) {
/* packet overflowed MRU */ /* packet overflowed MRU */