-stable review patch. If anyone has any objections, please let us know. ------------------ From: Al Viro 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 Signed-off-by: David S. Miller Signed-off-by: Chris Wright --- net/bridge/netfilter/ebtables.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) --- linux-2.6.19.orig/net/bridge/netfilter/ebtables.c +++ linux-2.6.19/net/bridge/netfilter/ebtables.c @@ -401,13 +401,17 @@ ebt_check_entry_size_and_hooks(struct eb 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 eb 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 eb 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 eb 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 -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/