[Xen-changelog] [qemu-xen stable-4.9] blkverify: Catch bs->exact_filename overflow

[patchbot@xxxxxxx]

commit 2d4685f6adee0f07fe19c89de61601b91e5874e1
Author:     Max Reitz <mreitz@xxxxxxxxxx>
AuthorDate: Tue Jun 13 19:20:06 2017 +0200
Commit:     Anthony PERARD <anthony.perard@xxxxxxxxxx>
CommitDate: Mon Jul 9 12:37:55 2018 +0100

    blkverify: Catch bs->exact_filename overflow
    
    The bs->exact_filename field may not be sufficient to store the full
    blkverify node filename. In this case, we should not generate a filename
    at all instead of an unusable one.
    
    Cc: qemu-stable@xxxxxxxxxx
    Reported-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
    Signed-off-by: Max Reitz <mreitz@xxxxxxxxxx>
    Message-id: 20170613172006.19685-3-mreitz@xxxxxxxxxx
    Reviewed-by: Alberto Garcia <berto@xxxxxxxxxx>
    Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
    Signed-off-by: Max Reitz <mreitz@xxxxxxxxxx>
    (cherry picked from commit 05cc758a3dfc79488d0a8eb7f5830a41871e78d0)
---
 block/blkverify.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/block/blkverify.c b/block/blkverify.c
index 28f9af6dba..201b2489f1 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -314,10 +314,14 @@ static void blkverify_refresh_filename(BlockDriverState 
*bs, QDict *options)
     if (bs->file->bs->exact_filename[0]
         && s->test_file->bs->exact_filename[0])
     {
-        snprintf(bs->exact_filename, sizeof(bs->exact_filename),
-                 "blkverify:%s:%s",
-                 bs->file->bs->exact_filename,
-                 s->test_file->bs->exact_filename);
+        int ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename),
+                           "blkverify:%s:%s",
+                           bs->file->bs->exact_filename,
+                           s->test_file->bs->exact_filename);
+        if (ret >= sizeof(bs->exact_filename)) {
+            /* An overflow makes the filename unusable, so do not report any */
+            bs->exact_filename[0] = 0;
+        }
     }
 }
 
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.9

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