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Commit 48bdf072 authored by Chris Metcalf's avatar Chris Metcalf Committed by David S. Miller
Browse files

ip_options_compile: properly handle unaligned pointer 



The current code takes an unaligned pointer and does htonl() on it to
make it big-endian, then does a memcpy().  The problem is that the
compiler decides that since the pointer is to a __be32, it is legal
to optimize the copy into a processor word store.  However, on an
architecture that does not handled unaligned writes in kernel space,
this produces an unaligned exception fault.

The solution is to track the pointer as a "char *" (which removes a bunch
of unpleasant casts in any case), and then just use put_unaligned_be32()
to write the value to memory.

Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
Signed-off-by: default avatarDavid S. Miller <davem@zippy.davemloft.net>
parent 11ad2f52

net/ipv4/ip_options.c

+8 −7
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/slab.h>

#include <linux/types.h>

#include <asm/uaccess.h>

#include <asm/unaligned.h>

#include <linux/skbuff.h>

#include <linux/ip.h>

#include <linux/icmp.h>
@@ -350,7 +351,7 @@ int ip_options_compile(struct net *net, 
				goto error;

			}

			if (optptr[2] <= optlen) {

				__be32 *timeptr = NULL;

				unsigned char *timeptr = NULL;

				if (optptr[2]+3 > optptr[1]) {

					pp_ptr = optptr + 2;

					goto error;
@@ -359,7 +360,7 @@ int ip_options_compile(struct net *net, 
				      case IPOPT_TS_TSONLY:

					opt->ts = optptr - iph;

					if (skb)

						timeptr = (__be32*)&optptr[optptr[2]-1];

						timeptr = &optptr[optptr[2]-1];

					opt->ts_needtime = 1;

					optptr[2] += 4;

					break;
@@ -371,7 +372,7 @@ int ip_options_compile(struct net *net, 
					opt->ts = optptr - iph;

					if (rt)  {

						memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);

						timeptr = (__be32*)&optptr[optptr[2]+3];

						timeptr = &optptr[optptr[2]+3];

					}

					opt->ts_needaddr = 1;

					opt->ts_needtime = 1;
@@ -389,7 +390,7 @@ int ip_options_compile(struct net *net, 
						if (inet_addr_type(net, addr) == RTN_UNICAST)

							break;

						if (skb)

							timeptr = (__be32*)&optptr[optptr[2]+3];

							timeptr = &optptr[optptr[2]+3];

					}

					opt->ts_needtime = 1;

					optptr[2] += 8;
@@ -403,10 +404,10 @@ int ip_options_compile(struct net *net, 
				}

				if (timeptr) {

					struct timespec tv;

					__be32  midtime;

					u32  midtime;

					getnstimeofday(&tv);

					midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);

					memcpy(timeptr, &midtime, sizeof(__be32));

					midtime = (tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC;

					put_unaligned_be32(midtime, timeptr);

					opt->is_changed = 1;

				}

			} else {