[PATCH] cifs: update new ACE pointer after populate_new_aces.

[Shyam Prasad N <nspmangalore@gmail.com>]

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Hi Steve,

Please consider this fix for the failing generic/317 test for cifsacl
and idsfromsid,modefromsid.
This is exposed on certain combinations of default ACEs on the file.

-- 
Regards,
Shyam

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From 8e206cd0dcf27e5c1885c56d318b205cb62a18cf Mon Sep 17 00:00:00 2001
From: Shyam Prasad N <sprasad@microsoft.com>
Date: Wed, 10 Mar 2021 10:22:27 +0000
Subject: [PATCH] cifs: update new ACE pointer after populate_new_aces.

After the fix for retaining externally set ACEs with cifsacl and
modefromsid,idsfromsid, there was an issue in populating the
inherited ACEs after setting the ACEs introduced by these two modes.
Fixed this by updating the ACE pointer again after the call to
populate_new_aces.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
---
 fs/cifs/cifsacl.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 9d29eb9660c2..2be22a5c690f 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -1118,7 +1118,6 @@ static int set_chmod_dacl(struct cifs_acl *pdacl, struct cifs_acl *pndacl,
 	/* Retain old ACEs which we can retain */
 	for (i = 0; i < src_num_aces; ++i) {
 		pntace = (struct cifs_ace *) (acl_base + size);
-		pnntace = (struct cifs_ace *) (nacl_base + nsize);
 
 		if (!new_aces_set && (pntace->flags & INHERITED_ACE)) {
 			/* Place the new ACEs in between existing explicit and inherited */
@@ -1131,14 +1130,18 @@ static int set_chmod_dacl(struct cifs_acl *pdacl, struct cifs_acl *pndacl,
 		}
 
 		/* If it's any one of the ACE we're replacing, skip! */
-		if ((compare_sids(&pntace->sid, &sid_unix_NFS_mode) == 0) ||
+		if (!mode_from_sid &&
+				((compare_sids(&pntace->sid, &sid_unix_NFS_mode) == 0) ||
 				(compare_sids(&pntace->sid, pownersid) == 0) ||
 				(compare_sids(&pntace->sid, pgrpsid) == 0) ||
 				(compare_sids(&pntace->sid, &sid_everyone) == 0) ||
-				(compare_sids(&pntace->sid, &sid_authusers) == 0)) {
+				(compare_sids(&pntace->sid, &sid_authusers) == 0))) {
 			goto next_ace;
 		}
 
+		/* update the pointer to the next ACE to populate*/
+		pnntace = (struct cifs_ace *) (nacl_base + nsize);
+
 		nsize += cifs_copy_ace(pnntace, pntace, NULL);
 		num_aces++;
 
-- 
2.25.1