From: Aki Tuomi <aki.tuomi@open-xchange.com>
Date: Tue, 30 Sep 2025 17:21:22 +0000 (+0300)
Subject: virtual: Allow mailbox_count header to be empty
X-Git-Tag: 2.4.2~360
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ac6302f8cac1770638a9f5202dfb86a41c7c57d3;p=thirdparty%2Fdovecot%2Fcore.git

virtual: Allow mailbox_count header to be empty

If no folders match, do not error out. Fixes
Error: Mailbox INBOX: virtual index INBOX: Broken mailbox_count header
---

diff --git a/src/plugins/virtual/virtual-sync.c b/src/plugins/virtual/virtual-sync.c
index db8ab9e2a3..99835a0ef3 100644
--- a/src/plugins/virtual/virtual-sync.c
+++ b/src/plugins/virtual/virtual-sync.c
@@ -265,7 +265,8 @@ int virtual_mailbox_ext_header_read(struct virtual_mailbox *mbox,
 		mailboxes = (const void *)(ext_hdr + 1);
 		ext_name_offset = sizeof(*ext_hdr) +
 			ext_hdr->mailbox_count * sizeof(*mailboxes);
-		if (ext_name_offset >= ext_size ||
+		if ((ext_name_offset == ext_size && ext_hdr->mailbox_count > 0) ||
+		    ext_name_offset > ext_size ||
 		    ext_hdr->mailbox_count > INT_MAX/sizeof(*mailboxes)) {
 			e_error(event,
 				"virtual index %s: Broken mailbox_count header",