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=1793743488; b=sF1GPlhJ2pvGWWm3KUSRM4DeDb9s2HuhpElZIslB9hLZr/Ox5vENQHi4+I3nacn6vMX9 Ie2Fs0JuEqExIw02lfLHg9J+yIz8pv7V8RyscpDjH8IlSiJlajZiTzp2pZYTSUtYHazyF 8lFjG/T2G4xzeNK8O9NNLFSgtPdtOszRqwZ4UvGCUfHTmkK94PuMRXcyKUutqb66/hvM/ 6B2vzCs0oCO6t+CDJlQLAAMjnfol7Bjie4SGcnUTWiiNtb100ZYx7z+uig/qg484qofcy 7pRdNYFhQFPD5E7iPAPYDuPHrHcM2G37mpfn0xWgho+36mmnV1lKsSgYpO5bWbgyB4w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793743488; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=MGthJCIPcjjSto+999lEi5wAg/18qV7BwoKfxaLdcHk=; b=XkRxpBviKV42pP54iyYRQRzEexSy3lClCPSuofMWwSZbiYZKQECLxUechqrJjo6xGwhM NtplJiYhlDfmF4NGmHOaJwQ+eRYNptxOKos9Ez9OIUj9xYccwkzeasMCJG1UNjm0E+hwO leyroV3GMX/+yNCWrVFdqUzkMudJH0J+rbrgSsEpBZO60Jznpklal+wLL4xaFhfG2haPG HvacemvStKP1TqFOYysd/PX1dV31MtRMZ17W52Z3pWvA3uEPEqt/GrsW7RCf+8uUcMMuD HWJg84M+Oekcdt+dbWAsQlWqUhY/gVtQ2fJfJp2l7XYq9KNDNIYQ6azoO6RpLmy/Nkg== 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=ZIXnqEG8; 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 EFF05606D803 for ; Tue, 3 Nov 2026 22:04:47 +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=ZIXnqEG8 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BC3B1F000C1; Tue, 3 Nov 2026 22:04:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793743487; bh=MGthJCIPcjjSto+999lEi5wAg/18qV7BwoKfxaLdcHk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZIXnqEG8hL/C/PZXH+ibndXCC9cS/kFVaIkuESqDDxg7NpsliMzQ3nLpwVKtfcVed 0ytWA8Ep0xUZptkPew9JQIp90VwTW28pmp34cjE1DvZD+LuK3BR6p0tajq3lwdO+Z3 m++yoiQ5W4A1u87OKyWRlDNI7QM3JYISa30O1Ce0WYdT7RjreLpYkB+maVRSSuyt2Y kX7M4KFNPetoKRjN7ZJuB7b/NTeZ/m2104QM0IleFGVBRRSgtdxkXLB2FhcztoBrwC j/xPjv5FzxvG/MOeAqZK3+K2/JLkHn7YUDN12w+TD4Cej5wQbLjPodmVTnwS/CC5po wi4uzX7dyQyxg== From: Sasha Levin To: stable@vger.kernel.org Cc: DaeMyung Kang , Namjae Jeon , Sasha Levin Subject: [PATCH 6.12.y] ksmbd: fix named stream write and EOF handling Date: Tue, 3 Nov 2026 17:04:45 -0500 Message-ID: <20261103215952.1549221-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110332-browsing-plentiful-ef07@gregkh> References: <2026110332-browsing-plentiful-ef07@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: adapted fp->stream.pos updates to fp->filp->f_pos because the separate stream position field is absent ] 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 5f752434be3cf..0ebf9644e5367 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -6525,6 +6525,8 @@ 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 2ec2c90aa7248..9e1cc0d1638a4 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -416,23 +416,21 @@ 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, @@ -445,6 +443,8 @@ 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, KSMBD_DEFAULT_GFP); @@ -473,13 +473,69 @@ 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, KSMBD_DEFAULT_GFP); + 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