[qemu-xen stable-4.14] nbd: Avoid off-by-one in long export name truncation

[patchbot@xxxxxxx]

commit 9380cb9de20b1554162eea9eb0e80209464ace50
Author:     Eric Blake <eblake@xxxxxxxxxx>
AuthorDate: Mon Jun 22 16:03:55 2020 -0500
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Wed Sep 2 19:06:19 2020 -0500

    nbd: Avoid off-by-one in long export name truncation
    
    When snprintf returns the same value as the buffer size, the final
    byte was truncated to ensure a NUL terminator.  Fortunately, such long
    export names are unusual enough, with no real impact other than what
    is displayed to the user.
    
    Fixes: 5c86bdf12089
    Reported-by: Max Reitz <mreitz@xxxxxxxxxx>
    Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
    Message-Id: <20200622210355.414941-1-eblake@xxxxxxxxxx>
    Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
    (cherry picked from commit 00d69986da83a74f6f5731c80f8dd09fde95d19a)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 block/nbd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/nbd.c b/block/nbd.c
index bfc0be6af6..bf3fbebfa0 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -2011,7 +2011,7 @@ static void nbd_refresh_filename(BlockDriverState *bs)
         len = snprintf(bs->exact_filename, sizeof(bs->exact_filename),
                        "nbd://%s:%s", host, port);
     }
-    if (len > sizeof(bs->exact_filename)) {
+    if (len >= sizeof(bs->exact_filename)) {
         /* Name is too long to represent exactly, so leave it empty. */
         bs->exact_filename[0] = '\0';
     }
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.14