FAILED: patch "[PATCH] ksmbd: fix potencial OOB in get_file_all_info() for compound" failed to apply to 5.15-stable tree

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 beef2634f81f1c086208191f7228bce1d366493d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026032931-tubby-automatic-2197@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From beef2634f81f1c086208191f7228bce1d366493d Mon Sep 17 00:00:00 2001
From: Namjae Jeon <[email protected]>
Date: Thu, 19 Mar 2026 21:00:02 +0900
Subject: [PATCH] ksmbd: fix potencial OOB in get_file_all_info() for compound
requests

When a compound request consists of QUERY_DIRECTORY + QUERY_INFO (FILE_ALL_INFORMATION) and the first command consumes nearly the entire max_trans_size, get_file_all_info() would blindly call smbConvertToUTF16() with PATH_MAX, causing out-of-bounds write beyond the response buffer. In get_file_all_info(), there was a missing validation check for the client-provided OutputBufferLength before copying the filename into FileName field of the smb2_file_all_info structure.
If the filename length exceeds the available buffer space, it could lead to potential buffer overflows or memory corruption during smbConvertToUTF16 conversion. This calculating the actual free buffer size using smb2_calc_max_out_buf_len() and returning -EINVAL if the buffer is insufficient and updating smbConvertToUTF16 to use the actual filename length (clamped by PATH_MAX) to ensure a safe copy operation.

index f5f1bf5f642e..6fb7a795ff5d 100644
@@ -4940,7 +4940,8 @@ static int get_file_all_info(struct ksmbd_work *work,
 	int conv_len;
 	char *filename;
 	u64 time;
-	int ret;
+	int ret, buf_free_len, filename_len;
+	struct smb2_query_info_req *req = ksmbd_req_buf_next(work);
 
 	if (!(fp->daccess & FILE_READ_ATTRIBUTES_LE)) {
 		ksmbd_debug(SMB, "no right to read the attributes : 0x%x\n",

@@ -4952,6 +4953,16 @@ static int get_file_all_info(struct ksmbd_work *work,
 	if (IS_ERR(filename))
 		return PTR_ERR(filename);
 
+	filename_len = strlen(filename);
+	buf_free_len = smb2_calc_max_out_buf_len(work,
+			offsetof(struct smb2_query_info_rsp, Buffer) +
+			offsetof(struct smb2_file_all_info, FileName),
+			le32_to_cpu(req->OutputBufferLength));
+	if (buf_free_len < (filename_len + 1) * 2) {
+		kfree(filename);
+		return -EINVAL;
+	}
+
 	ret = vfs_getattr(&fp->filp->f_path, &stat, STATX_BASIC_STATS,
 			  AT_STATX_SYNC_AS_STAT);
 	if (ret) {

@@ -4995,7 +5006,8 @@ static int get_file_all_info(struct ksmbd_work *work,
 	file_info->Mode = fp->coption;
 	file_info->AlignmentRequirement = 0;
 	conv_len = smbConvertToUTF16((__le16 *)file_info->FileName, filename,
-				     PATH_MAX, conn->local_nls, 0);
+				     min(filename_len, PATH_MAX),
+				     conn->local_nls, 0);
 	conv_len *= 2;
 	file_info->FileNameLength = cpu_to_le32(conv_len);
 	rsp->OutputBufferLength =

From: Namjae Jeon <[email protected]>

[ Upstream commit beef2634f81f1c086208191f7228bce1d366493d ]

When a compound request consists of QUERY_DIRECTORY + QUERY_INFO (FILE_ALL_INFORMATION) and the first command consumes nearly the entire max_trans_size, get_file_all_info() would blindly call smbConvertToUTF16() with PATH_MAX, causing out-of-bounds write beyond the response buffer. In get_file_all_info(), there was a missing validation check for the client-provided OutputBufferLength before copying the filename into FileName field of the smb2_file_all_info structure.
If the filename length exceeds the available buffer space, it could lead to potential buffer overflows or memory corruption during smbConvertToUTF16 conversion. This calculating the actual free buffer size using smb2_calc_max_out_buf_len() and returning -EINVAL if the buffer is insufficient and updating smbConvertToUTF16 to use the actual filename length (clamped by PATH_MAX) to ensure a safe copy operation.

---
 fs/ksmbd/smb2pdu.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

index b5ff4c855f9cb..07144891d9784 100644
@@ -4564,6 +4564,8 @@ static int get_file_all_info(struct ksmbd_work *work,
 	int conv_len;
 	char *filename;
 	u64 time;
+	int buf_free_len, filename_len;
+	struct smb2_query_info_req *req = ksmbd_req_buf_next(work);
 
 	if (!(fp->daccess & FILE_READ_ATTRIBUTES_LE)) {
 		ksmbd_debug(SMB, "no right to read the attributes : 0x%x\n",

@@ -4575,6 +4577,16 @@ static int get_file_all_info(struct ksmbd_work *work,
 	if (IS_ERR(filename))
 		return PTR_ERR(filename);
 
+	filename_len = strlen(filename);
+	buf_free_len = smb2_calc_max_out_buf_len(work,
+			offsetof(struct smb2_query_info_rsp, Buffer) +
+			offsetof(struct smb2_file_all_info, FileName),
+			le32_to_cpu(req->OutputBufferLength));
+	if (buf_free_len < (filename_len + 1) * 2) {
+		kfree(filename);
+		return -EINVAL;
+	}
+
 	inode = file_inode(fp->filp);
 	generic_fillattr(file_mnt_user_ns(fp->filp), inode, &stat);
 

@@ -4606,7 +4618,8 @@ static int get_file_all_info(struct ksmbd_work *work,
 	file_info->Mode = fp->coption;
 	file_info->AlignmentRequirement = 0;
 	conv_len = smbConvertToUTF16((__le16 *)file_info->FileName, filename,
-				     PATH_MAX, conn->local_nls, 0);
+				     min(filename_len, PATH_MAX),
+				     conn->local_nls, 0);
 	conv_len *= 2;
 	file_info->FileNameLength = cpu_to_le32(conv_len);
 	rsp->OutputBufferLength =

2.53.0