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[NETFILTER]: ebtables: don't compute gap before checking struct type

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We cannot compute the gap until we know we have a 'struct ebt_entry' and
not 'struct ebt_entries'.  Failure to check can cause crash.

Tested-by: Santiago Garcia Mantinan <manty@manty.net>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Chuck Ebbert 2007-01-04 12:17:44 -08:00 committed by David S. Miller
parent bbdc176a2f
commit 44f9a2fdc4
1 changed files with 2 additions and 1 deletions
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3
net/bridge/netfilter/ebtables.c
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@ -610,7 +610,7 @@ ebt_check_entry(struct ebt_entry *e, struct ebt_table_info *newinfo,
struct ebt_entry_target *t; struct ebt_entry_target *t;
struct ebt_target *target; struct ebt_target *target;
unsigned int i, j, hook = 0, hookmask = 0; unsigned int i, j, hook = 0, hookmask = 0;
size_t gap = e->next_offset - e->target_offset; size_t gap;
int ret; int ret;
/* don't mess with the struct ebt_entries */ /* don't mess with the struct ebt_entries */
@ -660,6 +660,7 @@ ebt_check_entry(struct ebt_entry *e, struct ebt_table_info *newinfo,
if (ret != 0) if (ret != 0)
goto cleanup_watchers; goto cleanup_watchers;
t = (struct ebt_entry_target *)(((char *)e) + e->target_offset); t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);
gap = e->next_offset - e->target_offset;
target = find_target_lock(t->u.name, &ret, &ebt_mutex); target = find_target_lock(t->u.name, &ret, &ebt_mutex);
if (!target) if (!target)
goto cleanup_watchers; goto cleanup_watchers;