Commit e466af75 authored by Eric Dumazet's avatar Eric Dumazet Committed by Pablo Neira Ayuso

netfilter: x_tables: avoid stack-out-of-bounds read in xt_copy_counters_from_user

syzkaller reports an out of bound read in strlcpy(), triggered
by xt_copy_counters_from_user()

Fix this by using memcpy(), then forcing a zero byte at the last position
of the destination, as Florian did for the non COMPAT code.

Fixes: d7591f0c ("netfilter: x_tables: introduce and use xt_copy_counters_from_user")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 5f9bfe0e
...@@ -892,7 +892,7 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len, ...@@ -892,7 +892,7 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0) if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0)
return ERR_PTR(-EFAULT); return ERR_PTR(-EFAULT);
strlcpy(info->name, compat_tmp.name, sizeof(info->name)); memcpy(info->name, compat_tmp.name, sizeof(info->name) - 1);
info->num_counters = compat_tmp.num_counters; info->num_counters = compat_tmp.num_counters;
user += sizeof(compat_tmp); user += sizeof(compat_tmp);
} else } else
...@@ -905,9 +905,9 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len, ...@@ -905,9 +905,9 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
if (copy_from_user(info, user, sizeof(*info)) != 0) if (copy_from_user(info, user, sizeof(*info)) != 0)
return ERR_PTR(-EFAULT); return ERR_PTR(-EFAULT);
info->name[sizeof(info->name) - 1] = '\0';
user += sizeof(*info); user += sizeof(*info);
} }
info->name[sizeof(info->name) - 1] = '\0';
size = sizeof(struct xt_counters); size = sizeof(struct xt_counters);
size *= info->num_counters; size *= info->num_counters;
......
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