[PATCH] ksmbd: fix out-of-bound read in deassemble_neg_contexts()

[PATCH] ksmbd: fix out-of-bound read in deassemble_neg_contexts()

[Namjae Jeon]

The check in the beginning is
`clen + sizeof(struct smb2_neg_context) <= len_of_ctxts`,
but in the end of loop, `len_of_ctxts` will subtract
`((clen + 7) & ~0x7) + sizeof(struct smb2_neg_context)`, which causes
integer underflow when clen does the 8 alignment. We should use
`(clen + 7) & ~0x7` in the check to avoid underflow from happening.

Then there are some variables that need to be declared unsigned
instead of signed.

[   11.671070] BUG: KASAN: slab-out-of-bounds in smb2_handle_negotiate+0x799/0x1610
[   11.671533] Read of size 2 at addr ffff888005e86cf2 by task kworker/0:0/7
...
[   11.673383] Call Trace:
[   11.673541]  <TASK>
[   11.673679]  dump_stack_lvl+0x33/0x50
[   11.673913]  print_report+0xcc/0x620
[   11.674671]  kasan_report+0xae/0xe0
[   11.675171]  kasan_check_range+0x35/0x1b0
[   11.675412]  smb2_handle_negotiate+0x799/0x1610
[   11.676217]  ksmbd_smb_negotiate_common+0x526/0x770
[   11.676795]  handle_ksmbd_work+0x274/0x810
...

Signed-off-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/smb2pdu.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 7a81541de602..25c0ba04c59d 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -963,13 +963,13 @@ static void decode_sign_cap_ctxt(struct ksmbd_conn *conn,
 
 static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn,
 				      struct smb2_negotiate_req *req,
-				      int len_of_smb)
+				      unsigned int len_of_smb)
 {
 	/* +4 is to account for the RFC1001 len field */
 	struct smb2_neg_context *pctx = (struct smb2_neg_context *)req;
 	int i = 0, len_of_ctxts;
-	int offset = le32_to_cpu(req->NegotiateContextOffset);
-	int neg_ctxt_cnt = le16_to_cpu(req->NegotiateContextCount);
+	unsigned int offset = le32_to_cpu(req->NegotiateContextOffset);
+	unsigned int neg_ctxt_cnt = le16_to_cpu(req->NegotiateContextCount);
 	__le32 status = STATUS_INVALID_PARAMETER;
 
 	ksmbd_debug(SMB, "decoding %d negotiate contexts\n", neg_ctxt_cnt);
@@ -983,7 +983,7 @@ static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn,
 	while (i++ < neg_ctxt_cnt) {
 		int clen, ctxt_len;
 
-		if (len_of_ctxts < sizeof(struct smb2_neg_context))
+		if (len_of_ctxts < (int)sizeof(struct smb2_neg_context))
 			break;
 
 		pctx = (struct smb2_neg_context *)((char *)pctx + offset);
@@ -1038,9 +1038,8 @@ static __le32 deassemble_neg_contexts(struct ksmbd_conn *conn,
 		}
 
 		/* offsets must be 8 byte aligned */
-		clen = (clen + 7) & ~0x7;
-		offset = clen + sizeof(struct smb2_neg_context);
-		len_of_ctxts -= clen + sizeof(struct smb2_neg_context);
+		offset = (ctxt_len + 7) & ~0x7;
+		len_of_ctxts -= offset;
 	}
 	return status;
 }
-- 
2.25.1

[PATCH] ksmbd: fix out-of-bound read in parse_lease_state()

[Namjae Jeon]

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

[PATCH] ksmbd: fix posix_acls and acls dereferencing possible ERR_PTR()

[Namjae Jeon]

Dan reported the following error message:

fs/smb/server/smbacl.c:1296 smb_check_perm_dacl()
    error: 'posix_acls' dereferencing possible ERR_PTR()
fs/smb/server/vfs.c:1323 ksmbd_vfs_make_xattr_posix_acl()
    error: 'posix_acls' dereferencing possible ERR_PTR()
fs/smb/server/vfs.c:1830 ksmbd_vfs_inherit_posix_acl()
    error: 'acls' dereferencing possible ERR_PTR()

__get_acl() returns a mix of error pointers and NULL. This change it
with IS_ERR_OR_NULL().

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/smbacl.c | 4 ++--
 fs/smb/server/vfs.c    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c
index 6d6cfb6957a9..0a5862a61c77 100644
--- a/fs/smb/server/smbacl.c
+++ b/fs/smb/server/smbacl.c
@@ -1290,7 +1290,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 
 	if (IS_ENABLED(CONFIG_FS_POSIX_ACL)) {
 		posix_acls = get_inode_acl(d_inode(path->dentry), ACL_TYPE_ACCESS);
-		if (posix_acls && !found) {
+		if (!IS_ERR_OR_NULL(posix_acls) && !found) {
 			unsigned int id = -1;
 
 			pa_entry = posix_acls->a_entries;
@@ -1314,7 +1314,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
 				}
 			}
 		}
-		if (posix_acls)
+		if (!IS_ERR_OR_NULL(posix_acls))
 			posix_acl_release(posix_acls);
 	}
 
diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 6f302919e9f7..f9fb778247e7 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -1321,7 +1321,7 @@ static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct mnt_idmap *id
 		return NULL;
 
 	posix_acls = get_inode_acl(inode, acl_type);
-	if (!posix_acls)
+	if (IS_ERR_OR_NULL(posix_acls))
 		return NULL;
 
 	smb_acl = kzalloc(sizeof(struct xattr_smb_acl) +
@@ -1830,7 +1830,7 @@ int ksmbd_vfs_inherit_posix_acl(struct mnt_idmap *idmap,
 		return -EOPNOTSUPP;
 
 	acls = get_inode_acl(parent_inode, ACL_TYPE_DEFAULT);
-	if (!acls)
+	if (IS_ERR_OR_NULL(acls))
 		return -ENOENT;
 	pace = acls->a_entries;
 
-- 
2.25.1

[PATCH] ksmbd: return a literal instead of 'err' in ksmbd_vfs_kern_path_locked()

[Namjae Jeon]

Return a literal instead of 'err' in ksmbd_vfs_kern_path_locked().

Fixes: 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---
 fs/smb/server/vfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index f9fb778247e7..4f14f111a367 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -1161,7 +1161,7 @@ int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,
 
 	err = ksmbd_vfs_path_lookup_locked(share_conf, name, flags, path);
 	if (!err)
-		return err;
+		return 0;
 
 	if (caseless) {
 		char *filepath;
-- 
2.25.1

Re: [PATCH] ksmbd: return a literal instead of 'err' in ksmbd_vfs_kern_path_locked()

[Dan Carpenter]

On Tue, May 30, 2023 at 09:57:57PM +0900, Namjae Jeon wrote:
> Return a literal instead of 'err' in ksmbd_vfs_kern_path_locked().
> 
> Fixes: 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name")

No need for a Fixes tag.

regards,
dan carpenter

Re: [PATCH] ksmbd: return a literal instead of 'err' in ksmbd_vfs_kern_path_locked()

[Namjae Jeon]

2023-05-30 23:01 GMT+09:00, Dan Carpenter <dan.carpenter@linaro.org>:
> On Tue, May 30, 2023 at 09:57:57PM +0900, Namjae Jeon wrote:
>> Return a literal instead of 'err' in ksmbd_vfs_kern_path_locked().
>>
>> Fixes: 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and
>> ->d_name")
>
> No need for a Fixes tag.
OK.

Thanks.
>
> regards,
> dan carpenter
>
>