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authorJohannes Berg <johannes.berg@intel.com>2019-01-26 21:12:19 +0100
committerDavid S. Miller <davem@davemloft.net>2019-01-27 23:11:55 -0800
commit50c2936634bcb1db78a8ca63249236810c11a80f (patch)
treee9e56ffd071a94a61c735de61a42ff749ca06dde /net
parentc69c29a1a0a8f68cd87e98ba4a5a79fb8ef2a58c (diff)
decnet: fix DN_IFREQ_SIZE
Digging through the ioctls with Al because of the previous patches, we found that on 64-bit decnet's dn_dev_ioctl() is wrong, because struct ifreq::ifr_ifru is actually 24 bytes (not 16 as expected from struct sockaddr) due to the ifru_map and ifru_settings members. Clearly, decnet expects the ioctl to be called with a struct like struct ifreq_dn { char ifr_name[IFNAMSIZ]; struct sockaddr_dn ifr_addr; }; since it does struct ifreq *ifr = ...; struct sockaddr_dn *sdn = (struct sockaddr_dn *)&ifr->ifr_addr; This means that DN_IFREQ_SIZE is too big for what it wants on 64-bit, as it is sizeof(struct ifreq) - sizeof(struct sockaddr) + sizeof(struct sockaddr_dn) This assumes that sizeof(struct sockaddr) is the size of ifr_ifru but that isn't true. Fix this to use offsetof(struct ifreq, ifr_ifru). This indeed doesn't really matter much - the result is that we copy in/out 8 bytes more than we should on 64-bit platforms. In case the "struct ifreq_dn" lands just on the end of a page though it might lead to faults. As far as I can tell, it has been like this forever, so it seems very likely that nobody cares. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/decnet/dn_dev.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
index d0b3e69c6b39..0962f9201baa 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -56,7 +56,7 @@
#include <net/dn_neigh.h>
#include <net/dn_fib.h>
-#define DN_IFREQ_SIZE (sizeof(struct ifreq) - sizeof(struct sockaddr) + sizeof(struct sockaddr_dn))
+#define DN_IFREQ_SIZE (offsetof(struct ifreq, ifr_ifru) + sizeof(struct sockaddr_dn))
static char dn_rt_all_end_mcast[ETH_ALEN] = {0xAB,0x00,0x00,0x04,0x00,0x00};
static char dn_rt_all_rt_mcast[ETH_ALEN] = {0xAB,0x00,0x00,0x03,0x00,0x00};