[PATCH] ksmbd: fail share config requests when path allocation fails

[Shuhao Fu <sfual@cse.ust.hk>]

Non-pipe shares must have a duplicated backing path before they can be
published. share_config_request() currently calls kstrndup() for that
path, but if the allocation fails it leaves ret unchanged. If veto list
parsing succeeds and share->name exists, the partially built share is
still inserted into the global share table with share->path left NULL.

A later share-root SMB2 create uses tree_conn->share_conf->path as the
lookup root. If the share was published with path == NULL, that request
passes a NULL pathname into do_getname_kernel()/strlen() and can crash
the ksmbd worker.

Set ret = -ENOMEM when path duplication fails so the incomplete share is
destroyed before publication.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
---
 fs/smb/server/mgmt/share_config.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/smb/server/mgmt/share_config.c b/fs/smb/server/mgmt/share_config.c
index 53f44ff4d376f3e..6f97f8d39657cd2 100644
--- a/fs/smb/server/mgmt/share_config.c
+++ b/fs/smb/server/mgmt/share_config.c
@@ -167,7 +167,10 @@ static struct ksmbd_share_config *share_config_request(struct ksmbd_work *work,
 
 		share->path = kstrndup(ksmbd_share_config_path(resp), path_len,
 				      KSMBD_DEFAULT_GFP);
-		if (share->path) {
+		if (!share->path) {
+			ret = -ENOMEM;
+		} else {
+			ret = 0;
 			share->path_sz = strlen(share->path);
 			while (share->path_sz > 1 &&
 			       share->path[share->path_sz - 1] == '/')
@@ -179,9 +182,10 @@ static struct ksmbd_share_config *share_config_request(struct ksmbd_work *work,
 		share->force_directory_mode = resp->force_directory_mode;
 		share->force_uid = resp->force_uid;
 		share->force_gid = resp->force_gid;
-		ret = parse_veto_list(share,
-				      KSMBD_SHARE_CONFIG_VETO_LIST(resp),
-				      resp->veto_list_sz);
+		if (!ret)
+			ret = parse_veto_list(share,
+					      KSMBD_SHARE_CONFIG_VETO_LIST(resp),
+					      resp->veto_list_sz);
 		if (!ret && share->path) {
 			if (__ksmbd_override_fsids(work, share)) {
 				kill_share(share);
-- 
2.49.0