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netfilter: ebtables: fix wrong name length while copying to user-space

user-space ebtables expects 32 bytes-long names, but xt_match names
use 29 bytes. We have to copy less 29 bytes and then, make sure we
fill the remaining bytes with zeroes.

Signed-off-by: Santosh Nayak <santoshprasadnayak@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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1 parent 2a15cd2 commit 848edc69192a38bf9d261032f248b14f47e6af8b Santosh Nayak committed with davem330 Mar 6, 2012
Showing with 13 additions and 3 deletions.
  1. +13 −3 net/bridge/netfilter/ebtables.c
@@ -1335,7 +1335,12 @@ static inline int ebt_make_matchname(const struct ebt_entry_match *m,
const char *base, char __user *ubase)
{
char __user *hlp = ubase + ((char *)m - base);
- if (copy_to_user(hlp, m->u.match->name, EBT_FUNCTION_MAXNAMELEN))
+ char name[EBT_FUNCTION_MAXNAMELEN] = {};
+
+ /* ebtables expects 32 bytes long names but xt_match names are 29 bytes
+ long. Copy 29 bytes and fill remaining bytes with zeroes. */
+ strncpy(name, m->u.match->name, sizeof(name));
+ if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
return -EFAULT;
return 0;
}
@@ -1344,7 +1349,10 @@ static inline int ebt_make_watchername(const struct ebt_entry_watcher *w,
const char *base, char __user *ubase)
{
char __user *hlp = ubase + ((char *)w - base);
- if (copy_to_user(hlp , w->u.watcher->name, EBT_FUNCTION_MAXNAMELEN))
+ char name[EBT_FUNCTION_MAXNAMELEN] = {};
+
+ strncpy(name, w->u.watcher->name, sizeof(name));
+ if (copy_to_user(hlp , name, EBT_FUNCTION_MAXNAMELEN))
return -EFAULT;
return 0;
}
@@ -1355,10 +1363,12 @@ ebt_make_names(struct ebt_entry *e, const char *base, char __user *ubase)
int ret;
char __user *hlp;
const struct ebt_entry_target *t;
+ char name[EBT_FUNCTION_MAXNAMELEN] = {};
if (e->bitmask == 0)
return 0;
+ strncpy(name, t->u.target->name, sizeof(name));
hlp = ubase + (((char *)e + e->target_offset) - base);
t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);
@@ -1368,7 +1378,7 @@ ebt_make_names(struct ebt_entry *e, const char *base, char __user *ubase)
ret = EBT_WATCHER_ITERATE(e, ebt_make_watchername, base, ubase);
if (ret != 0)
return ret;
- if (copy_to_user(hlp, t->u.target->name, EBT_FUNCTION_MAXNAMELEN))
+ if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
return -EFAULT;
return 0;
}

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