From: Xin Long Date: Tue, 2 Jun 2026 01:06:06 +0000 (-0400) Subject: sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=0861615c28de668669d748ef4eb913ea9262d13b;p=thirdparty%2Flinux.git sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing When a listening SCTP server processes a COOKIE_ECHO chunk, the cached peer INIT chunk embedded after the cookie is parsed and its parameters are later walked by sctp_process_init() using sctp_walk_params(). However, the chunk header length of this cached INIT chunk was not validated against the remaining buffer in the COOKIE_ECHO payload. If the length field is inflated, the parameter walk can run beyond the actual received data, leading to out-of-bounds reads and potential memory corruption during later parameter handling (e.g. STATE_COOKIE processing and kmemdup() copies). Add a bounds check in sctp_unpack_cookie() to ensure the cached INIT chunk length does not exceed the available data in the COOKIE_ECHO buffer before it is used. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Brian Geffon Signed-off-by: Xin Long Link: https://patch.msgid.link/eb60825fa22d6f9e663c7d4dbb69f397b5d34d42.1780362366.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski --- diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c index de86ac088289..85264862fb6b 100644 --- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -1730,6 +1730,7 @@ struct sctp_association *sctp_unpack_cookie( struct sctp_signed_cookie *cookie; struct sk_buff *skb = chunk->skb; struct sctp_cookie *bear_cookie; + struct sctp_chunkhdr *ch; enum sctp_scope scope; unsigned int len; ktime_t kt; @@ -1759,6 +1760,10 @@ struct sctp_association *sctp_unpack_cookie( cookie = chunk->subh.cookie_hdr; bear_cookie = &cookie->c; + ch = (struct sctp_chunkhdr *)(bear_cookie + 1); + if (ntohs(ch->length) > len - fixed_size) + goto malformed; + /* Verify the cookie's MAC, if cookie authentication is enabled. */ if (sctp_sk(ep->base.sk)->cookie_auth_enable) { u8 mac[SHA256_DIGEST_SIZE];