[Qemu-devel] [PATCH 62/79] blkverify: Catch bs->exact_filename overflow

[Michael Roth]

From: Max Reitz <address@hidden>

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: address@hidden
Reported-by: Qu Wenruo <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
Message-id: address@hidden
Reviewed-by: Alberto Garcia <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
(cherry picked from commit 05cc758a3dfc79488d0a8eb7f5830a41871e78d0)
Signed-off-by: Michael Roth <address@hidden>
---
 block/blkverify.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/block/blkverify.c b/block/blkverify.c
index 6b0a603..06369f9 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -301,10 +301,14 @@ 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;
+        }
     }
 }
 
-- 
2.7.4