All of lore.kernel.org
 help / color / mirror / Atom feed
From: Namjae Jeon <linkinjeon@kernel.org>
To: linux-cifs@vger.kernel.org
Cc: smfrench@gmail.com, senozhatsky@chromium.org, tom@talpey.com,
	atteh.mailbox@gmail.com, Namjae Jeon <linkinjeon@kernel.org>,
	Chih-Yen Chang <cc85nod@gmail.com>
Subject: [PATCH] ksmbd: fix out-of-bound read in parse_lease_state()
Date: Tue, 30 May 2023 21:57:55 +0900	[thread overview]
Message-ID: <20230530125757.12910-2-linkinjeon@kernel.org> (raw)
In-Reply-To: <20230530125757.12910-1-linkinjeon@kernel.org>

This bug is in parse_lease_state, and it is caused by the missing check
of `struct create_context`. When the ksmbd traverses the create_contexts,
it doesn't check if the field of `NameOffset` and `Next` is valid,
The KASAN message is following:

[    6.664323] BUG: KASAN: slab-out-of-bounds in parse_lease_state+0x7d/0x280
[    6.664738] Read of size 2 at addr ffff888005c08988 by task kworker/0:3/103
...
[    6.666644] Call Trace:
[    6.666796]  <TASK>
[    6.666933]  dump_stack_lvl+0x33/0x50
[    6.667167]  print_report+0xcc/0x620
[    6.667903]  kasan_report+0xae/0xe0
[    6.668374]  kasan_check_range+0x35/0x1b0
[    6.668621]  parse_lease_state+0x7d/0x280
[    6.668868]  smb2_open+0xbe8/0x4420
[    6.675137]  handle_ksmbd_work+0x282/0x820

Use smb2_find_context_vals() to find smb2 create request lease context.
smb2_find_context_vals validate create context fields.

Reported-by: Chih-Yen Chang <cc85nod@gmail.com>
Tested-by: Chih-Yen Chang <cc85nod@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/oplock.c | 66 +++++++++++++++---------------------------
 1 file changed, 24 insertions(+), 42 deletions(-)

diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c
index db181bdad73a..844b303baf29 100644
--- a/fs/smb/server/oplock.c
+++ b/fs/smb/server/oplock.c
@@ -1415,56 +1415,38 @@ void create_lease_buf(u8 *rbuf, struct lease *lease)
  */
 struct lease_ctx_info *parse_lease_state(void *open_req)
 {
-	char *data_offset;
 	struct create_context *cc;
-	unsigned int next = 0;
-	char *name;
-	bool found = false;
 	struct smb2_create_req *req = (struct smb2_create_req *)open_req;
-	struct lease_ctx_info *lreq = kzalloc(sizeof(struct lease_ctx_info),
-		GFP_KERNEL);
+	struct lease_ctx_info *lreq;
+
+	cc = smb2_find_context_vals(req, SMB2_CREATE_REQUEST_LEASE, 4);
+	if (IS_ERR_OR_NULL(cc))
+		return NULL;
+
+	lreq = kzalloc(sizeof(struct lease_ctx_info), GFP_KERNEL);
 	if (!lreq)
 		return NULL;
 
-	data_offset = (char *)req + le32_to_cpu(req->CreateContextsOffset);
-	cc = (struct create_context *)data_offset;
-	do {
-		cc = (struct create_context *)((char *)cc + next);
-		name = le16_to_cpu(cc->NameOffset) + (char *)cc;
-		if (le16_to_cpu(cc->NameLength) != 4 ||
-		    strncmp(name, SMB2_CREATE_REQUEST_LEASE, 4)) {
-			next = le32_to_cpu(cc->Next);
-			continue;
-		}
-		found = true;
-		break;
-	} while (next != 0);
+	if (sizeof(struct lease_context_v2) == le32_to_cpu(cc->DataLength)) {
+		struct create_lease_v2 *lc = (struct create_lease_v2 *)cc;
 
-	if (found) {
-		if (sizeof(struct lease_context_v2) == le32_to_cpu(cc->DataLength)) {
-			struct create_lease_v2 *lc = (struct create_lease_v2 *)cc;
-
-			memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
-			lreq->req_state = lc->lcontext.LeaseState;
-			lreq->flags = lc->lcontext.LeaseFlags;
-			lreq->duration = lc->lcontext.LeaseDuration;
-			memcpy(lreq->parent_lease_key, lc->lcontext.ParentLeaseKey,
-			       SMB2_LEASE_KEY_SIZE);
-			lreq->version = 2;
-		} else {
-			struct create_lease *lc = (struct create_lease *)cc;
+		memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
+		lreq->req_state = lc->lcontext.LeaseState;
+		lreq->flags = lc->lcontext.LeaseFlags;
+		lreq->duration = lc->lcontext.LeaseDuration;
+		memcpy(lreq->parent_lease_key, lc->lcontext.ParentLeaseKey,
+				SMB2_LEASE_KEY_SIZE);
+		lreq->version = 2;
+	} else {
+		struct create_lease *lc = (struct create_lease *)cc;
 
-			memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
-			lreq->req_state = lc->lcontext.LeaseState;
-			lreq->flags = lc->lcontext.LeaseFlags;
-			lreq->duration = lc->lcontext.LeaseDuration;
-			lreq->version = 1;
-		}
-		return lreq;
+		memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
+		lreq->req_state = lc->lcontext.LeaseState;
+		lreq->flags = lc->lcontext.LeaseFlags;
+		lreq->duration = lc->lcontext.LeaseDuration;
+		lreq->version = 1;
 	}
-
-	kfree(lreq);
-	return NULL;
+	return lreq;
 }
 
 /**
-- 
2.25.1


  reply	other threads:[~2023-05-30 13:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-30 12:57 [PATCH] ksmbd: fix out-of-bound read in deassemble_neg_contexts() Namjae Jeon
2023-05-30 12:57 ` Namjae Jeon [this message]
2023-05-30 12:57 ` [PATCH] ksmbd: fix posix_acls and acls dereferencing possible ERR_PTR() Namjae Jeon
2023-05-30 12:57 ` [PATCH] ksmbd: return a literal instead of 'err' in ksmbd_vfs_kern_path_locked() Namjae Jeon
2023-05-30 14:01   ` Dan Carpenter
2023-05-30 14:12     ` Namjae Jeon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230530125757.12910-2-linkinjeon@kernel.org \
    --to=linkinjeon@kernel.org \
    --cc=atteh.mailbox@gmail.com \
    --cc=cc85nod@gmail.com \
    --cc=linux-cifs@vger.kernel.org \
    --cc=senozhatsky@chromium.org \
    --cc=smfrench@gmail.com \
    --cc=tom@talpey.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.