From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793745588; b=Pq5KrrJKr+bG42+nFJ6q5Y3+iQoBTuiAvP8n66Unqmv/0DKuK6S8UUI5OLy+dpo4EN1F hxw2Uv7AZKpAsjlyLRNzIFlw7FTFm+kQZh6FrfXpwnPvynom9VofmCTiX1XlNqkBlFerf mLPr2TR79VsMoZuZO5A6KwX7K4lXGW0kb/BUL28k+q9h7F7YDcGa20aF4nyHqJYtr9at4 v0alEJIlfAAJCabFmtByZg5G1ja24QHHt5SeHIVeDTBgPnFFiBpjBsjzKgCqxdPilDe40 OgiQzQTraNpadQ2dp+Hb1k63YIc9IjqkDLjWf3Wyr7DFBHjTk8empyWEh0SSuB5ZLKw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793745588; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=aZIe3kT6amkhzi0XYW9ak/In12ZN3+Lm3m8pB82JAsM=; b=gLCV0mtRnnvD9+vB+HKnfHoyvIQY/a8jcll/6h0PWdeGRz7qky0kfXbkgpWNwYAE7Nm0 ObzvRbMlzM3kbVxvh6nCX1wmvAbvLT76piVM4lnasaSQryuc0bFuZrdrhRGJ/QX4G57J1 eUnRAnDIxMXEfMj/mc0mKcXh2pwCQ81ITdD7Vj9Dhifur8VPzr6Ys7qPMADyKOHvd73sq x/NH4yF4D1jnWYam6AJz260Bb+QYYsUPo1Zj6D127pAUFRlHKv47HL2u3JBySN3+qz3d4 rx3q72qse6ahv+sY9xN3IPSjrTl6+KGQYoubI2qkO27xMAT7AXUaQ34uSArmihKrm8w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=FSAKyIwh; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD80D606A31B for ; Tue, 3 Nov 2026 22:39:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=FSAKyIwh Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDBEF1F000C1; Tue, 3 Nov 2026 22:39:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793745587; bh=aZIe3kT6amkhzi0XYW9ak/In12ZN3+Lm3m8pB82JAsM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FSAKyIwhSsHpo21XFYzVBnqDoCrOOpQhVU/IgHNyyCknocUe00TTjxonoKbMkWpty 7TncvCDKKMV/xNhfqIm4h9ff+xOgJYXZ0VkQiaf4LfjHtZztTvYTaU2XLlbaVCP2Kq JBu12RcpnuvamL8dleFzD2KEUyDpK94wUimTmiQlDJEvRmRxGxn0a1SG/sOcuWaxJk ie5CvDu7dTSwHtftd2gwM1I2vWHBcePSnvB4alKRlbvk8hsXsGGEg7+bJ7eQdLxbpD bjOz3VyJFCGCji71/0Qhm51aZMvKBwlCYhC9/xPdX0O+84xUVIH2aAaSh6Vl8r3UX3 8CTDd2ZTYwDuA== From: Sasha Levin To: stable@vger.kernel.org Cc: DaeMyung Kang , Namjae Jeon , Sasha Levin Subject: [PATCH 6.6.y] ksmbd: fix named stream write and EOF handling Date: Tue, 3 Nov 2026 17:39:45 -0500 Message-ID: <20261103223846.1614932-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110333-coke-seismic-b0a6@gregkh> References: <2026110333-coke-seismic-b0a6@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: DaeMyung Kang [ Upstream commit 02165c8d402392278a5cd2cf97645ed73a7ad4a1 ] An SMB WRITE to an existing named stream can silently discard data after its written range. ksmbd stores streams as xattr values, but the write path passes offset + count as the length of the replacement xattr even when the old stream is longer. Writing 26 bytes at offset 0 to a 60-byte stream reports 26 bytes written while discarding the remaining 34 bytes. Keep the existing xattr length when an in-place write ends before EOF. Reject writes that cross XATTR_SIZE_MAX rather than storing only the portion that fits while reporting the full requested count. Commit 4ea0bb8aaedf ("ksmbd: handle set/get info file for streamed file") intentionally skipped ordinary inode truncation for stream handles: an EOF SetInfo on an ADS had truncated the base file. That fixed the base file corruption but left stream EOF changes reporting success without resizing the stream. Handle these requests by resizing only the stream xattr; the base file size remains untouched. Zero-fill stream extensions. This is needed alongside the write fix: a short write's accidental truncation previously masked an ignored explicit EOF change. The stream resize helper returns xattr errors directly rather than using the base-file truncate path's EBADF conversion. Fixes: f44158485826 ("cifsd: add file operations") Fixes: 4ea0bb8aaedf ("ksmbd: handle set/get info file for streamed file") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang Signed-off-by: Namjae Jeon [ sashal: Used fp->filp->f_pos instead of the unavailable fp->stream.pos to store the stream write position. ] Signed-off-by: Sasha Levin --- fs/smb/server/smb2pdu.c | 2 ++ fs/smb/server/vfs.c | 72 ++++++++++++++++++++++++++++++++++++----- fs/smb/server/vfs.h | 1 + 3 files changed, 67 insertions(+), 8 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index aaccef2e3f3bb..7906e7e747d83 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -6497,6 +6497,8 @@ static int set_end_of_file_info(struct ksmbd_work *work, struct ksmbd_file *fp, newsize = le64_to_cpu(file_eof_info->EndOfFile); inode = file_inode(fp->filp); + if (ksmbd_stream_fd(fp)) + return ksmbd_vfs_stream_truncate(fp, newsize); /* * If FILE_END_OF_FILE_INFORMATION of set_info_file is called diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c index aed2d2dd9b25a..4daae499769ae 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -417,23 +417,21 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos, const struct cred *saved_cred; char *stream_buf = NULL, *wbuf; struct mnt_idmap *idmap = file_mnt_idmap(fp->filp); - size_t size; + size_t size, write_end; ssize_t v_len; int err = 0; ksmbd_debug(VFS, "write stream data pos : %llu, count : %zd\n", *pos, count); - if (*pos >= XATTR_SIZE_MAX) { + if (*pos < 0 || *pos >= XATTR_SIZE_MAX) { pr_err("stream write position %lld is out of bounds\n", *pos); return -EINVAL; } - size = *pos + count; - if (size > XATTR_SIZE_MAX) { - size = XATTR_SIZE_MAX; - count = XATTR_SIZE_MAX - *pos; - } + if (count > XATTR_SIZE_MAX - *pos) + return -EFBIG; + write_end = *pos + count; saved_cred = override_creds(fp->filp->f_cred); v_len = ksmbd_vfs_getcasexattr(idmap, @@ -446,6 +444,8 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos, err = v_len; goto out_revert; } + /* Preserve the tail of an existing stream on an in-place write. */ + size = max_t(size_t, v_len, write_end); if (v_len < size) { wbuf = kvzalloc(size, GFP_KERNEL); @@ -474,13 +474,69 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos, if (err < 0) goto out; - fp->filp->f_pos = *pos; + fp->filp->f_pos = write_end; err = 0; out: kvfree(stream_buf); return err; } +/** + * ksmbd_vfs_stream_truncate() - change the length of a named stream + * @fp: stream file handle + * @newsize: new stream length + * + * Resize the stream xattr without changing the base inode size. + * + * Return: 0 on success, otherwise a negative error code + */ +int ksmbd_vfs_stream_truncate(struct ksmbd_file *fp, loff_t newsize) +{ + const struct cred *saved_cred; + struct mnt_idmap *idmap = file_mnt_idmap(fp->filp); + char *stream_buf = NULL, *new_buf = NULL; + ssize_t v_len; + int err; + + if (newsize < 0) + return -EINVAL; + if (newsize > XATTR_SIZE_MAX) + return -EFBIG; + + saved_cred = override_creds(fp->filp->f_cred); + v_len = ksmbd_vfs_getcasexattr(idmap, fp->filp->f_path.dentry, + fp->stream.name, fp->stream.size, + &stream_buf); + if (v_len < 0) { + err = v_len; + goto out; + } + if (v_len == newsize) { + err = 0; + goto out; + } + + new_buf = stream_buf; + if (newsize > v_len) { + new_buf = kvzalloc(newsize, GFP_KERNEL); + if (!new_buf) { + err = -ENOMEM; + goto out; + } + if (v_len) + memcpy(new_buf, stream_buf, v_len); + } + + err = ksmbd_vfs_setxattr(idmap, &fp->filp->f_path, fp->stream.name, + new_buf, newsize, 0, true); + if (new_buf != stream_buf) + kvfree(new_buf); +out: + kvfree(stream_buf); + revert_creds(saved_cred); + return err; +} + /** * ksmbd_vfs_write() - vfs helper for smb file write * @work: work diff --git a/fs/smb/server/vfs.h b/fs/smb/server/vfs.h index 06903024a2d88..526c0541ec691 100644 --- a/fs/smb/server/vfs.h +++ b/fs/smb/server/vfs.h @@ -82,6 +82,7 @@ int ksmbd_vfs_read(struct ksmbd_work *work, struct ksmbd_file *fp, size_t count, int ksmbd_vfs_write(struct ksmbd_work *work, struct ksmbd_file *fp, char *buf, size_t count, loff_t *pos, bool sync, ssize_t *written); +int ksmbd_vfs_stream_truncate(struct ksmbd_file *fp, loff_t newsize); int ksmbd_vfs_fsync(struct ksmbd_work *work, u64 fid, u64 p_id); int ksmbd_vfs_remove_file(struct ksmbd_work *work, const struct path *path); int ksmbd_vfs_link(struct ksmbd_work *work, -- 2.53.0