{"id":2220132,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2220132/?format=json","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/1.0/projects/12/?format=json","name":"Linux CIFS Client","link_name":"linux-cifs-client","list_id":"linux-cifs.vger.kernel.org","list_email":"linux-cifs@vger.kernel.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<2026040647-reset-uninstall-1145@gregkh>","date":"2026-04-06T13:46:48","name":"[3/3] ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"5487e4700b13cb5409913143b30c361f4296fddf","submitter":{"id":11800,"url":"http://patchwork.ozlabs.org/api/1.0/people/11800/?format=json","name":"Greg Kroah-Hartman","email":"gregkh@linuxfoundation.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/2026040647-reset-uninstall-1145@gregkh/mbox/","series":[{"id":498855,"url":"http://patchwork.ozlabs.org/api/1.0/series/498855/?format=json","date":"2026-04-06T13:46:46","name":"ksmbd: some potential bugfixes","version":1,"mbox":"http://patchwork.ozlabs.org/series/498855/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2220132/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-cifs@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org\n header.a=rsa-sha256 header.s=korg header.b=1eJ/mcVd;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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a=openpgp-sha256; l=2611;\n i=gregkh@linuxfoundation.org; h=from:subject:message-id;\n bh=4ZQRFVzdUCijd8idg1rAWi6+HbzaURjFDDhmzLTKBPU=;\n b=owGbwMvMwCRo6H6F97bub03G02pJDJmXd7r/q+V5ZHeAwbvDvqp/SfnK1mPVKXOYVNkEjO9sM\n GLf1LCyI5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACby/inDggW+lQWPis6FrDjd\n 9qXZy/aMh1uLN8P8qJq4zVP3X2FRvaw0p+9s3ovlekfcAA==","X-Developer-Key":"i=gregkh@linuxfoundation.org; a=openpgp;\n fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29","Content-Transfer-Encoding":"8bit"},"content":"The kernel ASN.1 BER decoder calls action callbacks incrementally as it\nwalks the input. When ksmbd_decode_negTokenInit() reaches the mechToken\n[2] OCTET STRING element, ksmbd_neg_token_alloc() allocates\nconn->mechToken immediately via kmemdup_nul(). If a later element in\nthe same blob is malformed, then the decoder will return nonzero after\nthe allocation is already live. This could happen if mechListMIC [3]\noverrunse the enclosing SEQUENCE.\n\ndecode_negotiation_token() then sets conn->use_spnego = false because\nboth the negTokenInit and negTokenTarg grammars failed. The cleanup at\nthe bottom of smb2_sess_setup() is gated on use_spnego:\n\n\tif (conn->use_spnego && conn->mechToken) {\n\t\tkfree(conn->mechToken);\n\t\tconn->mechToken = NULL;\n\t}\n\nso the kfree is skipped, causing the mechToken to never be freed.\n\nThis codepath is reachable pre-authentication, so untrusted clients can\ncause slow memory leaks on a server without even being properly\nauthenticated.\n\nFix this up by not checking check for use_spnego, as it's not required,\nso the memory will always be properly freed. At the same time, always\nfree the memory in ksmbd_conn_free() incase some other failure path\nforgot to free it.\n\nCc: Namjae Jeon \nCc: Steve French \nCc: Sergey Senozhatsky \nCc: Tom Talpey \nCc: linux-cifs@vger.kernel.org\nCc: stable \nAssisted-by: gregkh_clanker_t1000\nSigned-off-by: Greg Kroah-Hartman \n---\n fs/smb/server/connection.c | 1 +\n fs/smb/server/smb2pdu.c | 2 +-\n 2 files changed, 2 insertions(+), 1 deletion(-)","diff":"diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c\nindex 1bb2081c492c..26cfce344861 100644\n--- a/fs/smb/server/connection.c\n+++ b/fs/smb/server/connection.c\n@@ -96,6 +96,7 @@ void ksmbd_conn_free(struct ksmbd_conn *conn)\n \txa_destroy(&conn->sessions);\n \tkvfree(conn->request_buf);\n \tkfree(conn->preauth_info);\n+\tkfree(conn->mechToken);\n \tif (atomic_dec_and_test(&conn->refcnt)) {\n \t\tconn->transport->ops->free_transport(conn->transport);\n \t\tkfree(conn);\ndiff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c\nindex 6f658dc20758..a344937595f4 100644\n--- a/fs/smb/server/smb2pdu.c\n+++ b/fs/smb/server/smb2pdu.c\n@@ -1915,7 +1915,7 @@ int smb2_sess_setup(struct ksmbd_work *work)\n \telse if (rc)\n \t\trsp->hdr.Status = STATUS_LOGON_FAILURE;\n \n-\tif (conn->use_spnego && conn->mechToken) {\n+\tif (conn->mechToken) {\n \t\tkfree(conn->mechToken);\n \t\tconn->mechToken = NULL;\n \t}\n","prefixes":["3/3"]}