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authorGustavo A. R. Silva <gustavoars@kernel.org>2021-07-31 20:08:30 +0300
committerDavid S. Miller <davem@davemloft.net>2021-08-02 17:17:28 +0300
commit2d3e5caf96b9449af951e63476657acd759c1a30 (patch)
treeb89b846db9bca30a8863daa2243ae0297e4f14ac /net/ipv4/ip_sockglue.c
parent29a097b7747725da003245412dab61093d4e5976 (diff)
downloadlinux-2d3e5caf96b9449af951e63476657acd759c1a30.tar.xz
net/ipv4: Replace one-element array with flexible-array member
There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. Use an anonymous union with a couple of anonymous structs in order to keep userspace unchanged: $ pahole -C ip_msfilter net/ipv4/ip_sockglue.o struct ip_msfilter { union { struct { __be32 imsf_multiaddr_aux; /* 0 4 */ __be32 imsf_interface_aux; /* 4 4 */ __u32 imsf_fmode_aux; /* 8 4 */ __u32 imsf_numsrc_aux; /* 12 4 */ __be32 imsf_slist[1]; /* 16 4 */ }; /* 0 20 */ struct { __be32 imsf_multiaddr; /* 0 4 */ __be32 imsf_interface; /* 4 4 */ __u32 imsf_fmode; /* 8 4 */ __u32 imsf_numsrc; /* 12 4 */ __be32 imsf_slist_flex[0]; /* 16 0 */ }; /* 0 16 */ }; /* 0 20 */ /* size: 20, cachelines: 1, members: 1 */ /* last cacheline: 20 bytes */ }; Also, refactor the code accordingly and make use of the struct_size() and flex_array_size() helpers. This helps with the ongoing efforts to globally enable -Warray-bounds and get us closer to being able to tighten the FORTIFY_SOURCE routines on memcpy(). [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/79 Link: https://github.com/KSPP/linux/issues/109 Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_sockglue.c')
-rw-r--r--net/ipv4/ip_sockglue.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index ec6036713e2c..bbe660b84a91 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -663,12 +663,11 @@ static int set_mcast_msfilter(struct sock *sk, int ifindex,
struct sockaddr_storage *group,
struct sockaddr_storage *list)
{
- int msize = IP_MSFILTER_SIZE(numsrc);
struct ip_msfilter *msf;
struct sockaddr_in *psin;
int err, i;
- msf = kmalloc(msize, GFP_KERNEL);
+ msf = kmalloc(struct_size(msf, imsf_slist_flex, numsrc), GFP_KERNEL);
if (!msf)
return -ENOBUFS;
@@ -684,7 +683,7 @@ static int set_mcast_msfilter(struct sock *sk, int ifindex,
if (psin->sin_family != AF_INET)
goto Eaddrnotavail;
- msf->imsf_slist[i] = psin->sin_addr.s_addr;
+ msf->imsf_slist_flex[i] = psin->sin_addr.s_addr;
}
err = ip_mc_msfilter(sk, msf, ifindex);
kfree(msf);
@@ -1229,7 +1228,7 @@ static int do_ip_setsockopt(struct sock *sk, int level, int optname,
{
struct ip_msfilter *msf;
- if (optlen < IP_MSFILTER_SIZE(0))
+ if (optlen < struct_size(msf, imsf_slist_flex, 0))
goto e_inval;
if (optlen > sysctl_optmem_max) {
err = -ENOBUFS;
@@ -1247,7 +1246,8 @@ static int do_ip_setsockopt(struct sock *sk, int level, int optname,
err = -ENOBUFS;
break;
}
- if (IP_MSFILTER_SIZE(msf->imsf_numsrc) > optlen) {
+ if (struct_size(msf, imsf_slist_flex, msf->imsf_numsrc) >
+ optlen) {
kfree(msf);
err = -EINVAL;
break;
@@ -1660,11 +1660,12 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
{
struct ip_msfilter msf;
- if (len < IP_MSFILTER_SIZE(0)) {
+ if (len < struct_size(&msf, imsf_slist_flex, 0)) {
err = -EINVAL;
goto out;
}
- if (copy_from_user(&msf, optval, IP_MSFILTER_SIZE(0))) {
+ if (copy_from_user(&msf, optval,
+ struct_size(&msf, imsf_slist_flex, 0))) {
err = -EFAULT;
goto out;
}