diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2006-12-04 13:11:24 +0100 |
|---|---|---|
| committer | Adrian Bunk <bunk@stusta.de> | 2006-12-04 13:11:24 +0100 |
| commit | d559dd79b58829f1ebb7996698e6354600e79b14 (patch) | |
| tree | 1e4f2088a0fbf6875006d618cbad1ad609e2f60d /net | |
| parent | b00b3fe3f00962fc9faa7d34c28f5a20074c728b (diff) | |
[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>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Diffstat (limited to 'net')
| -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 cbd4020cc84d..a3e23c3c4ae5 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -422,13 +422,17 @@ 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 @@ -449,11 +453,8 @@ 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 */ @@ -476,6 +477,8 @@ 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) { @@ -487,10 +490,16 @@ 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 |