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Message-ID: <20240929125317.p7tbwvzy4bcs2a3s@pali>
Date: Sun, 29 Sep 2024 14:53:17 +0200
From: Pali Rohár <pali@...nel.org>
To: Steve French <sfrench@...ba.org>, Paulo Alcantara <pc@...guebit.com>,
Ronnie Sahlberg <ronniesahlberg@...il.com>
Cc: linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/8] cifs: Remove intermediate object of failed create
reparse call
Hello Steve, I was reading again implementation of smb2_compound_op()
function and if I understood it correctly, then out_iov and out_buftype
array parameters needs to have num_cmds+2 members. This is quite
unexpected, and this patch cause buffer overflow and memory leaks.
+2 is for CREATE and CLOSE operations added automatically by compound.
Surprisingly, no memory issue and neither corrupted packed I observed.
And therefore I thought that change is working fine.
I will send a new version of this change to increase array members and
free all members of array.
On Saturday 28 September 2024 23:59:42 Pali Rohár wrote:
> If CREATE was successful but SMB2_OP_SET_REPARSE failed then remove the
> intermediate object created by CREATE. Otherwise empty object stay on the
> server when reparse call failed.
>
> This ensures that if the creating of special files is unsupported by the
> server then no empty file stay on the server as a result of unsupported
> operation.
>
> Fixes: 102466f303ff ("smb: client: allow creating special files via reparse points")
> Signed-off-by: Pali Rohár <pali@...nel.org>
> ---
> fs/smb/client/smb2inode.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
> index 11a1c53c64e0..af42f44bdcf4 100644
> --- a/fs/smb/client/smb2inode.c
> +++ b/fs/smb/client/smb2inode.c
> @@ -1205,6 +1205,8 @@ struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data,
> struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
> struct cifsFileInfo *cfile;
> struct inode *new = NULL;
> + int out_buftype[2] = {};
> + struct kvec out_iov[2];
> struct kvec in_iov[2];
> int cmds[2];
> int rc;
> @@ -1228,7 +1230,7 @@ struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data,
> cmds[1] = SMB2_OP_POSIX_QUERY_INFO;
> cifs_get_writable_path(tcon, full_path, FIND_WR_ANY, &cfile);
> rc = smb2_compound_op(xid, tcon, cifs_sb, full_path, &oparms,
> - in_iov, cmds, 2, cfile, NULL, NULL, NULL);
> + in_iov, cmds, 2, cfile, out_iov, out_buftype, NULL);
> if (!rc) {
> rc = smb311_posix_get_inode_info(&new, full_path,
> data, sb, xid);
> @@ -1237,12 +1239,27 @@ struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data,
> cmds[1] = SMB2_OP_QUERY_INFO;
> cifs_get_writable_path(tcon, full_path, FIND_WR_ANY, &cfile);
> rc = smb2_compound_op(xid, tcon, cifs_sb, full_path, &oparms,
> - in_iov, cmds, 2, cfile, NULL, NULL, NULL);
> + in_iov, cmds, 2, cfile, out_iov, out_buftype, NULL);
> if (!rc) {
> rc = cifs_get_inode_info(&new, full_path,
> data, sb, xid, NULL);
> }
> }
> +
> + if (rc) {
> + /*
> + * If CREATE was successful but SMB2_OP_SET_REPARSE failed then
> + * remove the intermediate object created by CREATE. Otherwise
> + * empty object stay on the server when reparse call failed.
> + */
> + if (((struct smb2_hdr *)out_iov[0].iov_base)->Status == STATUS_SUCCESS &&
> + ((struct smb2_hdr *)out_iov[1].iov_base)->Status != STATUS_SUCCESS)
> + smb2_unlink(xid, tcon, full_path, cifs_sb, NULL);
> + }
> +
> + free_rsp_buf(out_buftype[0], out_iov[0].iov_base);
> + free_rsp_buf(out_buftype[1], out_iov[1].iov_base);
> +
> return rc ? ERR_PTR(rc) : new;
> }
>
> --
> 2.20.1
>
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