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FAILED: patch "[PATCH] ksmbd: fix OOB write in QUERY_INFO for compound requests" failed to apply to 5.15-stable tree

PATCH [email protected] 1 participant 1 message Apr 7

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Stable branch Kernel SMB3 server (ksmbd)
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The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x fda9522ed6afaec45cabc198d8492270c394c7bc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026040727-spindle-thigh-9ebd@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fda9522ed6afaec45cabc198d8492270c394c7bc Mon Sep 17 00:00:00 2001
From: Asim Viladi Oglu Manizada <[email protected]>
Date: Wed, 25 Mar 2026 09:14:22 +0900
Subject: [PATCH] ksmbd: fix OOB write in QUERY_INFO for compound requests

When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor.

The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs.

This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning.

Cc [email protected]
Fixes e2b76ab8b5c9 ("ksmbd: add support for read compound")
Signed-off-by Asim Viladi Oglu Manizada <[email protected]>
Signed-off-by Namjae Jeon <[email protected]>
Signed-off-by Steve French <[email protected]>
fs/smb/server/smb2pdu.c +89 -32
index 6fb7a795ff5d..8e4cfdc0ba02 100644
@@ -3402,20 +3402,24 @@ int smb2_open(struct ksmbd_work *work)
 							   KSMBD_SHARE_FLAG_ACL_XATTR)) {
 					struct smb_fattr fattr;
 					struct smb_ntsd *pntsd;
-					int pntsd_size, ace_num = 0;
+					int pntsd_size;
+					size_t scratch_len;
 
 					ksmbd_acls_fattr(&fattr, idmap, inode);
-					if (fattr.cf_acls)
-						ace_num = fattr.cf_acls->a_count;
-					if (fattr.cf_dacls)
-						ace_num += fattr.cf_dacls->a_count;
+					scratch_len = smb_acl_sec_desc_scratch_len(&fattr,
+							NULL, 0,
+							OWNER_SECINFO | GROUP_SECINFO |
+							DACL_SECINFO);
+					if (!scratch_len || scratch_len == SIZE_MAX) {
+						rc = -EFBIG;
+						posix_acl_release(fattr.cf_acls);
+						posix_acl_release(fattr.cf_dacls);
+						goto err_out;
+					}
 
-					pntsd = kmalloc(sizeof(struct smb_ntsd) +
-							sizeof(struct smb_sid) * 3 +
-							sizeof(struct smb_acl) +
-							sizeof(struct smb_ace) * ace_num * 2,
-							KSMBD_DEFAULT_GFP);
+					pntsd = kvzalloc(scratch_len, KSMBD_DEFAULT_GFP);
 					if (!pntsd) {
+						rc = -ENOMEM;
 						posix_acl_release(fattr.cf_acls);
 						posix_acl_release(fattr.cf_dacls);
 						goto err_out;

@@ -3430,7 +3434,7 @@ int smb2_open(struct ksmbd_work *work)
 					posix_acl_release(fattr.cf_acls);
 					posix_acl_release(fattr.cf_dacls);
 					if (rc) {
-						kfree(pntsd);
+						kvfree(pntsd);
 						goto err_out;
 					}
 

@@ -3440,7 +3444,7 @@ int smb2_open(struct ksmbd_work *work)
 								    pntsd,
 								    pntsd_size,
 								    false);
-					kfree(pntsd);
+					kvfree(pntsd);
 					if (rc)
 						pr_err("failed to store ntacl in xattr : %d\n",
 						       rc);

@@ -5372,8 +5376,9 @@ static int smb2_get_info_file(struct ksmbd_work *work,
 	if (test_share_config_flag(work->tcon->share_conf,
 				   KSMBD_SHARE_FLAG_PIPE)) {
 		/* smb2 info file called for pipe */
-		return smb2_get_info_file_pipe(work->sess, req, rsp,
+		rc = smb2_get_info_file_pipe(work->sess, req, rsp,
 					       work->response_buf);
+		goto iov_pin_out;
 	}
 
 	if (work->next_smb2_rcv_hdr_off) {

@@ -5473,6 +5478,12 @@ static int smb2_get_info_file(struct ksmbd_work *work,
 		rc = buffer_check_err(le32_to_cpu(req->OutputBufferLength),
 				      rsp, work->response_buf);
 	ksmbd_fd_put(work, fp);
+
+iov_pin_out:
+	if (!rc)
+		rc = ksmbd_iov_pin_rsp(work, (void *)rsp,
+				offsetof(struct smb2_query_info_rsp, Buffer) +
+				le32_to_cpu(rsp->OutputBufferLength));
 	return rc;
 }
 

@@ -5699,6 +5710,11 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	rc = buffer_check_err(le32_to_cpu(req->OutputBufferLength),
 			      rsp, work->response_buf);
 	path_put(&path);
+
+	if (!rc)
+		rc = ksmbd_iov_pin_rsp(work, (void *)rsp,
+				offsetof(struct smb2_query_info_rsp, Buffer) +
+				le32_to_cpu(rsp->OutputBufferLength));
 	return rc;
 }
 

@@ -5708,13 +5724,14 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 {
 	struct ksmbd_file *fp;
 	struct mnt_idmap *idmap;
-	struct smb_ntsd *pntsd = (struct smb_ntsd *)rsp->Buffer, *ppntsd = NULL;
+	struct smb_ntsd *pntsd = NULL, *ppntsd = NULL;
 	struct smb_fattr fattr = {{0}};
 	struct inode *inode;
 	__u32 secdesclen = 0;
 	unsigned int id = KSMBD_NO_FID, pid = KSMBD_NO_FID;
 	int addition_info = le32_to_cpu(req->AdditionalInformation);
-	int rc = 0, ppntsd_size = 0;
+	int rc = 0, ppntsd_size = 0, max_len;
+	size_t scratch_len = 0;
 
 	if (addition_info & ~(OWNER_SECINFO | GROUP_SECINFO | DACL_SECINFO |
 			      PROTECTED_DACL_SECINFO |

@@ -5722,6 +5739,11 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 		ksmbd_debug(SMB, "Unsupported addition info: 0x%x)\n",
 		       addition_info);
 
+		pntsd = kzalloc(ALIGN(sizeof(struct smb_ntsd), 8),
+				KSMBD_DEFAULT_GFP);
+		if (!pntsd)
+			return -ENOMEM;
+
 		pntsd->revision = cpu_to_le16(1);
 		pntsd->type = cpu_to_le16(SELF_RELATIVE | DACL_PROTECTED);
 		pntsd->osidoffset = 0;

@@ -5730,9 +5752,7 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 		pntsd->dacloffset = 0;
 
 		secdesclen = sizeof(struct smb_ntsd);
-		rsp->OutputBufferLength = cpu_to_le32(secdesclen);
-
-		return 0;
+		goto iov_pin;
 	}
 
 	if (work->next_smb2_rcv_hdr_off) {

@@ -5764,18 +5784,58 @@ static int smb2_get_info_sec(struct ksmbd_work *work,
 						     &ppntsd);
 
 	/* Check if sd buffer size exceeds response buffer size */
-	if (smb2_resp_buf_len(work, 8) > ppntsd_size)
-		rc = build_sec_desc(idmap, pntsd, ppntsd, ppntsd_size,
-				    addition_info, &secdesclen, &fattr);
+	max_len = smb2_calc_max_out_buf_len(work,
+			offsetof(struct smb2_query_info_rsp, Buffer),
+			le32_to_cpu(req->OutputBufferLength));
+	if (max_len < 0) {
+		rc = -EINVAL;
+		goto release_acl;
+	}
+
+	scratch_len = smb_acl_sec_desc_scratch_len(&fattr, ppntsd,
+			ppntsd_size, addition_info);
+	if (!scratch_len || scratch_len == SIZE_MAX) {
+		rc = -EFBIG;
+		goto release_acl;
+	}
+
+	pntsd = kvzalloc(scratch_len, KSMBD_DEFAULT_GFP);
+	if (!pntsd) {
+		rc = -ENOMEM;
+		goto release_acl;
+	}
+
+	rc = build_sec_desc(idmap, pntsd, ppntsd, ppntsd_size,
+			addition_info, &secdesclen, &fattr);
+
+release_acl:
 	posix_acl_release(fattr.cf_acls);
 	posix_acl_release(fattr.cf_dacls);
 	kfree(ppntsd);
 	ksmbd_fd_put(work, fp);
-	if (rc)
-		return rc;
 
+	if (!rc && ALIGN(secdesclen, 8) > scratch_len)
+		rc = -EFBIG;
+	if (rc)
+		goto err_out;
+
+iov_pin:
 	rsp->OutputBufferLength = cpu_to_le32(secdesclen);
-	return 0;
+	rc = buffer_check_err(le32_to_cpu(req->OutputBufferLength),
+			      rsp, work->response_buf);
+	if (rc)
+		goto err_out;
+
+	rc = ksmbd_iov_pin_rsp_read(work, (void *)rsp,
+			offsetof(struct smb2_query_info_rsp, Buffer),
+			pntsd, secdesclen);
+err_out:
+	if (rc) {
+		rsp->OutputBufferLength = 0;
+		kvfree(pntsd);
+	}
+
+	return rc;
 }
 
 /**

@@ -5799,6 +5859,9 @@ int smb2_query_info(struct ksmbd_work *work)
 		goto err_out;
 	}
 
+	rsp->StructureSize = cpu_to_le16(9);
+	rsp->OutputBufferOffset = cpu_to_le16(72);
+
 	switch (req->InfoType) {
 	case SMB2_O_INFO_FILE:
 		ksmbd_debug(SMB, "GOT SMB2_O_INFO_FILE\n");

@@ -5819,14 +5882,6 @@ int smb2_query_info(struct ksmbd_work *work)
 	}
 	ksmbd_revert_fsids(work);
 
-	if (!rc) {
-		rsp->StructureSize = cpu_to_le16(9);
-		rsp->OutputBufferOffset = cpu_to_le16(72);
-		rc = ksmbd_iov_pin_rsp(work, (void *)rsp,
-				       offsetof(struct smb2_query_info_rsp, Buffer) +
-					le32_to_cpu(rsp->OutputBufferLength));
-	}
-
 err_out:
 	if (rc < 0) {
 		if (rc == -EACCES)

@@ -5837,6 +5892,8 @@ int smb2_query_info(struct ksmbd_work *work)
 			rsp->hdr.Status = STATUS_UNEXPECTED_IO_ERROR;
 		else if (rc == -ENOMEM)
 			rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES;
+		else if (rc == -EINVAL && rsp->hdr.Status == 0)
+			rsp->hdr.Status = STATUS_INVALID_PARAMETER;
 		else if (rc == -EOPNOTSUPP || rsp->hdr.Status == 0)
 			rsp->hdr.Status = STATUS_INVALID_INFO_CLASS;
 		smb2_set_err_rsp(work);
fs/smb/server/smbacl.c +43 -0

49 lines not on this page · raw message

fs/smb/server/smbacl.h +2 -0
index 355adaee39b8..ab21ba2cd4df 100644
@@ -101,6 +101,8 @@ int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
 		 bool type_check, bool get_write);
 void id_to_sid(unsigned int cid, uint sidtype, struct smb_sid *ssid);
 void ksmbd_init_domain(u32 *sub_auth);
+size_t smb_acl_sec_desc_scratch_len(struct smb_fattr *fattr,
+		struct smb_ntsd *ppntsd, int ppntsd_size, int addition_info);
 
 static inline uid_t posix_acl_uid_translate(struct mnt_idmap *idmap,
 					    struct posix_acl_entry *pace)