Commit 5c1acf3f authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

cifs: fix regression when mounting shares with prefix paths 



The commit 315db9a0 ("cifs: fix leak in cifs_smb3_do_mount() ctx")
revealed an existing bug when mounting shares that contain a prefix
path or DFS links.

cifs_setup_volume_info() requires the @devname to contain the full
path (UNC + prefix) to update the fs context with the new UNC and
prepath values, however we were passing only the UNC
path (old_ctx->UNC) in @device thus discarding any prefix paths.

Instead of concatenating both old_ctx->{UNC,prepath} and pass it in
@devname, just keep the dup'ed values of UNC and prepath in
cifs_sb->ctx after calling smb3_fs_context_dup(), and fix
smb3_parse_devname() to correctly parse and not leak the new UNC and
prefix paths.

Cc: <stable@vger.kernel.org> # v5.11+
Fixes: 315db9a0 ("cifs: fix leak in cifs_smb3_do_mount() ctx")
Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: default avatarDavid Disseldorp <ddiss@suse.de>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 5b2abdaf

fs/cifs/cifsfs.c

+1 −7
Original line number Diff line number Diff line
@@ -863,13 +863,7 @@ cifs_smb3_do_mount(struct file_system_type *fs_type, 
		goto out;

	}



	/* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */

	kfree(cifs_sb->ctx->UNC);

	cifs_sb->ctx->UNC = NULL;

	kfree(cifs_sb->ctx->prepath);

	cifs_sb->ctx->prepath = NULL;



	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);

	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);

	if (rc) {

		root = ERR_PTR(rc);

		goto out;

fs/cifs/connect.c

+18 −6
Original line number Diff line number Diff line
@@ -3149,17 +3149,29 @@ static int do_dfs_failover(const char *path, const char *full_path, struct cifs_ 
int

cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const char *devname)

{

	int rc = 0;

	int rc;



	smb3_parse_devname(devname, ctx);

	if (devname) {

		cifs_dbg(FYI, "%s: devname=%s\n", __func__, devname);

		rc = smb3_parse_devname(devname, ctx);

		if (rc) {

			cifs_dbg(VFS, "%s: failed to parse %s: %d\n", __func__, devname, rc);

			return rc;

		}

	}



	if (mntopts) {

		char *ip;



		cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts);

		rc = smb3_parse_opt(mntopts, "ip", &ip);

		if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip,

						 strlen(ip))) {

		if (rc) {

			cifs_dbg(VFS, "%s: failed to parse ip options: %d\n", __func__, rc);

			return rc;

		}



		rc = cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip));

		kfree(ip);

		if (!rc) {

			cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);

			return -EINVAL;

		}
@@ -3179,7 +3191,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c 
		return -EINVAL;

	}



	return rc;

	return 0;

}



static int

fs/cifs/fs_context.c

+4 −0
Original line number Diff line number Diff line
@@ -476,6 +476,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx) 


	/* move "pos" up to delimiter or NULL */

	pos += len;

	kfree(ctx->UNC);

	ctx->UNC = kstrndup(devname, pos - devname, GFP_KERNEL);

	if (!ctx->UNC)

		return -ENOMEM;
@@ -486,6 +487,9 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx) 
	if (*pos == '/' || *pos == '\\')

		pos++;



	kfree(ctx->prepath);

	ctx->prepath = NULL;



	/* If pos is NULL then no prepath */

	if (!*pos)

		return 0;