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author | Johannes Berg <johannes.berg@intel.com> | 2019-01-26 23:12:19 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-05 17:37:56 +0300 |
commit | b89c62555ab774d816c7b3d341cfb9f3b27c7a59 (patch) | |
tree | 593c5c710829c71852a6ea70352dedeed187cf1b /net/decnet | |
parent | 35e074ebdadb8f2f186d189269b05fd3297b2341 (diff) | |
download | linux-b89c62555ab774d816c7b3d341cfb9f3b27c7a59.tar.xz |
decnet: fix DN_IFREQ_SIZE
[ Upstream commit 50c2936634bcb1db78a8ca63249236810c11a80f ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/decnet')
-rw-r--r-- | net/decnet/dn_dev.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c index df042b6d80b8..22876a197ebe 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}; |