diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2006-11-30 19:22:42 -0800 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2006-12-02 21:31:53 -0800 |
| commit | bb2ef25c2c62444b8fdb0346a23658a419803df9 (patch) | |
| tree | b16356c4da5e33704db570324380ddf44908ae44 /net/bridge | |
| parent | b6332e6cf9c9198c0f3b0fe37c2c57514dafe1b8 (diff) | |
| download | lwn-bb2ef25c2c62444b8fdb0346a23658a419803df9.tar.gz lwn-bb2ef25c2c62444b8fdb0346a23658a419803df9.zip | |
[EBTABLES]: Fix wraparounds in ebt_entries verification.
We need to verify that
a) we are not too close to the end of buffer to dereference
b) next entry we'll be checking won't be _before_ our
While we are at it, don't subtract unrelated pointers...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge')
| -rw-r--r-- | net/bridge/netfilter/ebtables.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index 9f85666f29f7..0dcebf20d6ce 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -401,13 +401,17 @@ ebt_check_entry_size_and_hooks(struct ebt_entry *e, struct ebt_entries **hook_entries, unsigned int *n, unsigned int *cnt, unsigned int *totalcnt, unsigned int *udc_cnt, unsigned int valid_hooks) { + unsigned int offset = (char *)e - newinfo->entries; + size_t left = (limit - base) - offset; int i; + if (left < sizeof(unsigned int)) + goto Esmall; + for (i = 0; i < NF_BR_NUMHOOKS; i++) { if ((valid_hooks & (1 << i)) == 0) continue; - if ( (char *)hook_entries[i] - base == - (char *)e - newinfo->entries) + if ((char *)hook_entries[i] == base + offset) break; } /* beginning of a new chain @@ -428,11 +432,8 @@ ebt_check_entry_size_and_hooks(struct ebt_entry *e, return -EINVAL; } /* before we look at the struct, be sure it is not too big */ - if ((char *)hook_entries[i] + sizeof(struct ebt_entries) - > limit) { - BUGPRINT("entries_size too small\n"); - return -EINVAL; - } + if (left < sizeof(struct ebt_entries)) + goto Esmall; if (((struct ebt_entries *)e)->policy != EBT_DROP && ((struct ebt_entries *)e)->policy != EBT_ACCEPT) { /* only RETURN from udc */ @@ -455,6 +456,8 @@ ebt_check_entry_size_and_hooks(struct ebt_entry *e, return 0; } /* a plain old entry, heh */ + if (left < sizeof(struct ebt_entry)) + goto Esmall; if (sizeof(struct ebt_entry) > e->watchers_offset || e->watchers_offset > e->target_offset || e->target_offset >= e->next_offset) { @@ -466,10 +469,16 @@ ebt_check_entry_size_and_hooks(struct ebt_entry *e, BUGPRINT("target size too small\n"); return -EINVAL; } + if (left < e->next_offset) + goto Esmall; (*cnt)++; (*totalcnt)++; return 0; + +Esmall: + BUGPRINT("entries_size too small\n"); + return -EINVAL; } struct ebt_cl_stack |