diff options
Diffstat (limited to 'epan/dissectors/packet-windows-common.c')
| -rw-r--r-- | epan/dissectors/packet-windows-common.c | 113 |
1 files changed, 90 insertions, 23 deletions
diff --git a/epan/dissectors/packet-windows-common.c b/epan/dissectors/packet-windows-common.c index 7a46b2b122..c3b75fe655 100644 --- a/epan/dissectors/packet-windows-common.c +++ b/epan/dissectors/packet-windows-common.c @@ -2004,23 +2004,23 @@ dissect_nt_sec_desc_type(tvbuff_t *tvb, int offset, proto_tree *parent_tree) int dissect_nt_sec_desc(tvbuff_t *tvb, int offset, packet_info *pinfo, - proto_tree *parent_tree, guint8 *drep, int len, + proto_tree *parent_tree, guint8 *drep, + gboolean len_supplied, int len, struct access_mask_info *ami) { proto_item *item = NULL; proto_tree *tree = NULL; guint16 revision; - int old_offset = offset; + int start_offset = offset; + int item_offset, end_offset; guint32 owner_sid_offset; guint32 group_sid_offset; guint32 sacl_offset; guint32 dacl_offset; - if(parent_tree){ - item = proto_tree_add_text(parent_tree, tvb, offset, len, - "NT Security Descriptor"); - tree = proto_item_add_subtree(item, ett_nt_sec_desc); - } + item = proto_tree_add_text(parent_tree, tvb, offset, -1, + "NT Security Descriptor"); + tree = proto_item_add_subtree(item, ett_nt_sec_desc); /* revision */ revision = tvb_get_letohs(tvb, offset); @@ -2028,7 +2028,6 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset, packet_info *pinfo, tvb, offset, 2, revision); offset += 2; - switch(revision){ case 1: /* only version we will ever see of this structure?*/ /* type */ @@ -2036,52 +2035,120 @@ dissect_nt_sec_desc(tvbuff_t *tvb, int offset, packet_info *pinfo, /* offset to owner sid */ owner_sid_offset = tvb_get_letohl(tvb, offset); - proto_tree_add_text(tree, tvb, offset, 4, "Offset to owner SID: %u", owner_sid_offset); + if(owner_sid_offset != 0 && owner_sid_offset < 20){ + /* Bogus value - points into fixed portion of descriptor */ + proto_tree_add_text(tree, tvb, offset, 4, "Offset to owner SID: %u (bogus, must be >= 20)", owner_sid_offset); + owner_sid_offset = 0; + } else + proto_tree_add_text(tree, tvb, offset, 4, "Offset to owner SID: %u", owner_sid_offset); offset += 4; /* offset to group sid */ group_sid_offset = tvb_get_letohl(tvb, offset); - proto_tree_add_text(tree, tvb, offset, 4, "Offset to group SID: %u", group_sid_offset); + if(group_sid_offset != 0 && group_sid_offset < 20){ + /* Bogus value - points into fixed portion of descriptor */ + proto_tree_add_text(tree, tvb, offset, 4, "Offset to group SID: %u (bogus, must be >= 20)", group_sid_offset); + group_sid_offset = 0; + } else + proto_tree_add_text(tree, tvb, offset, 4, "Offset to group SID: %u", group_sid_offset); offset += 4; /* offset to sacl */ sacl_offset = tvb_get_letohl(tvb, offset); - proto_tree_add_text(tree, tvb, offset, 4, "Offset to SACL: %u", sacl_offset); + if(sacl_offset != 0 && sacl_offset < 20){ + /* Bogus value - points into fixed portion of descriptor */ + proto_tree_add_text(tree, tvb, offset, 4, "Offset to SACL: %u (bogus, must be >= 20)", sacl_offset); + sacl_offset = 0; + } else + proto_tree_add_text(tree, tvb, offset, 4, "Offset to SACL: %u", sacl_offset); offset += 4; /* offset to dacl */ dacl_offset = tvb_get_letohl(tvb, offset); - proto_tree_add_text(tree, tvb, offset, 4, "Offset to DACL: %u", dacl_offset); + if(dacl_offset != 0 && dacl_offset < 20){ + /* Bogus value - points into fixed portion of descriptor */ + proto_tree_add_text(tree, tvb, offset, 4, "Offset to DACL: %u (bogus, must be >= 20)", dacl_offset); + dacl_offset = 0; + } else + proto_tree_add_text(tree, tvb, offset, 4, "Offset to DACL: %u", dacl_offset); offset += 4; + end_offset = offset; + /*owner SID*/ if(owner_sid_offset){ - if (len == -1) - offset = dissect_nt_sid(tvb, offset, tree, "Owner", NULL, -1); - else - dissect_nt_sid( - tvb, old_offset+owner_sid_offset, tree, "Owner", NULL, -1); + item_offset = start_offset+owner_sid_offset; + if (item_offset < start_offset) { + /* + * Overflow - throw an exception. + */ + THROW(ReportedBoundsError); + } + offset = dissect_nt_sid(tvb, item_offset, tree, "Owner", NULL, -1); + if (offset > end_offset) + end_offset = offset; } /*group SID*/ if(group_sid_offset){ - dissect_nt_sid( - tvb, old_offset+group_sid_offset, tree, "Group", NULL, -1); + item_offset = start_offset+group_sid_offset; + if (item_offset < start_offset) { + /* + * Overflow - throw an exception. + */ + THROW(ReportedBoundsError); + } + offset = dissect_nt_sid(tvb, item_offset, tree, "Group", NULL, -1); + if (offset > end_offset) + end_offset = offset; } /* sacl */ if(sacl_offset){ - dissect_nt_acl(tvb, old_offset+sacl_offset, pinfo, tree, - drep, "System (SACL)", ami); + item_offset = start_offset+sacl_offset; + if (item_offset < start_offset) { + /* + * Overflow - throw an exception. + */ + THROW(ReportedBoundsError); + } + offset = dissect_nt_acl(tvb, item_offset, pinfo, tree, + drep, "System (SACL)", ami); + if (offset > end_offset) + end_offset = offset; } /* dacl */ if(dacl_offset){ - dissect_nt_acl(tvb, old_offset+dacl_offset, pinfo, tree, - drep, "User (DACL)", ami); + item_offset = start_offset+dacl_offset; + if (item_offset < start_offset) { + /* + * Overflow - throw an exception. + */ + THROW(ReportedBoundsError); + } + offset = dissect_nt_acl(tvb, item_offset, pinfo, tree, + drep, "User (DACL)", ami); + if (offset > end_offset) + end_offset = offset; } + break; + default: + end_offset = offset; + break; + } + if (len_supplied) { + /* Make sure the length isn't too large (so that we get an + overflow) */ + tvb_ensure_bytes_exist(tvb, start_offset, len); + } else { + /* The length of the security descriptor is the difference + between the starting offset and the offset past the last + item in the descriptor. */ + len = end_offset - start_offset; } + proto_item_set_len(item, len); return offset+len; } |