{"id":2224783,"url":"http://patchwork.ozlabs.org/api/patches/2224783/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260418154505.84684-1-akif.sait111@gmail.com/","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/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":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260418154505.84684-1-akif.sait111@gmail.com>","list_archive_url":null,"date":"2026-04-18T15:45:05","name":"ksmbd: fix O(N^2) DoS in smb2_lock via unbounded LockCount","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"5f2f01d61e09ab3d45be6d6618c612654bfd027f","submitter":{"id":93185,"url":"http://patchwork.ozlabs.org/api/people/93185/?format=json","name":"Akif Sait","email":"akif.sait111@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260418154505.84684-1-akif.sait111@gmail.com/mbox/","series":[{"id":500450,"url":"http://patchwork.ozlabs.org/api/series/500450/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=500450","date":"2026-04-18T15:45:05","name":"ksmbd: fix O(N^2) DoS in smb2_lock via unbounded LockCount","version":1,"mbox":"http://patchwork.ozlabs.org/series/500450/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224783/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224783/checks/","tags":{},"related":[],"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 (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=f9cbbP1T;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c15:e001:75::12fc:5321; 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With no cap on\nLockCount a single authenticated request with LockCount=65535 results in\nroughly 2.1 billion iterations inside a ksmbd worker thread, pinning the\nCPU completely. A few concurrent requests hang the host entirely.\n\nCap lock_count at 64. The MS-SMB2 spec defines Open.LockSequenceArray\nas exactly 64 entries so 64 is the intended ceiling. No real workload\ncomes close to this in a single request.\n\nLet me know if you need more info or a reproducer.\n\nThanks,\nAkif\n\n\n fs/smb/server/smb2pdu.c | 2 +-\n 1 file changed, 1 insertion(+), 1 deletion(-)","diff":"diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c\nindex ee32e61b6d3c..012f0c3585a0 100644\n--- a/fs/smb/server/smb2pdu.c\n+++ b/fs/smb/server/smb2pdu.c\n@@ -7492,7 +7492,7 @@ int smb2_lock(struct ksmbd_work *work)\n \tlock_ele = req->locks;\n \n \tksmbd_debug(SMB, \"lock count is %d\\n\", lock_count);\n-\tif (!lock_count) {\n+\tif (!lock_count || lock_count > 64) {\n \t\terr = -EINVAL;\n \t\tgoto out2;\n \t}\n","prefixes":[]}