6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long [ Upstream commit 6f4c80a2a7e6d06753b89a578b710a2499a5e62b ] sctp_unpack_cookie() only checked that the embedded INIT chunk length did not exceed the remaining cookie payload, but did not ensure that the INIT chunk is large enough to contain a complete INIT header. A malformed COOKIE_ECHO can therefore carry a truncated INIT chunk whose length field is smaller than sizeof(struct sctp_init_chunk). Later, sctp_process_init() accesses INIT parameters unconditionally, which may lead to out-of-bounds reads. In addition, raw_addr_list_len is not fully validated against the remaining cookie payload. When cookie authentication is disabled, an attacker can supply an oversized raw_addr_list_len and cause sctp_raw_to_bind_addrs() to read beyond the end of the cookie. The address parser also lacks sufficient bounds checks for parameter headers and lengths, allowing malformed address parameters to trigger out-of-bounds reads. Fix this by: - requiring the embedded INIT chunk length to be at least sizeof(struct sctp_init_chunk); - validating that the INIT chunk and raw address list together fit within the cookie payload; - verifying sufficient data exists for each address parameter header and payload before parsing it. Note that sctp_verify_init() must be called after sctp_unpack_cookie() and before sctp_process_init() when cookie authentication is disabled. This will be addressed in a separate patch. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Sashiko Signed-off-by: Xin Long Link: https://patch.msgid.link/75af23a89adf881a0895d511775e4770da367cbf.1780873427.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sctp/bind_addr.c | 11 ++++++++++- net/sctp/sm_make_chunk.c | 12 +++++++++++- 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c index 6b95d3ba8fe1c..0947b276d1e08 100644 --- a/net/sctp/bind_addr.c +++ b/net/sctp/bind_addr.c @@ -275,6 +275,16 @@ int sctp_raw_to_bind_addrs(struct sctp_bind_addr *bp, __u8 *raw_addr_list, param = (struct sctp_paramhdr *)raw_addr_list; rawaddr = (union sctp_addr_param *)raw_addr_list; + if (addrs_len < sizeof(*param)) { + retval = -EINVAL; + goto out_err; + } + len = ntohs(param->length); + if (addrs_len < len) { + retval = -EINVAL; + goto out_err; + } + af = sctp_get_af_specific(param_type2af(param->type)); if (unlikely(!af) || !af->from_addr_param(&addr, rawaddr, htons(port), 0)) { @@ -291,7 +301,6 @@ int sctp_raw_to_bind_addrs(struct sctp_bind_addr *bp, __u8 *raw_addr_list, goto out_err; next: - len = ntohs(param->length); addrs_len -= len; raw_addr_list += len; } diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c index ec3a9363d22c6..73b5c0dba69fa 100644 --- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -1750,8 +1750,9 @@ struct sctp_association *sctp_unpack_cookie( struct sk_buff *skb = chunk->skb; struct sctp_cookie *bear_cookie; __u8 *digest = ep->digest; + struct sctp_chunkhdr *ch; enum sctp_scope scope; - unsigned int len; + unsigned int len, chlen; ktime_t kt; /* Header size is static data prior to the actual cookie, including @@ -1779,6 +1780,15 @@ struct sctp_association *sctp_unpack_cookie( cookie = chunk->subh.cookie_hdr; bear_cookie = &cookie->c; + ch = (struct sctp_chunkhdr *)(bear_cookie + 1); + chlen = ntohs(ch->length); + if (chlen < sizeof(struct sctp_init_chunk)) + goto malformed; + if (chlen > len - fixed_size) + goto malformed; + if (bear_cookie->raw_addr_list_len > len - fixed_size - chlen) + goto malformed; + if (!sctp_sk(ep->base.sk)->hmac) goto no_hmac; -- 2.53.0