[1/2] blkdebug: Catch bs->exact_filename overflow
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Message ID 20170613172006.19685-2-mreitz@redhat.com
State New
Headers show

Commit Message

Max Reitz June 13, 2017, 5:20 p.m. UTC
The bs->exact_filename field may not be sufficient to store the full
blkdebug node filename. In this case, we should not generate a filename
at all instead of an unusable one.

Cc: qemu-stable@nongnu.org
Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkdebug.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

Patch
diff mbox

diff --git a/block/blkdebug.c b/block/blkdebug.c
index a5196e8..6166d6a 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -840,9 +840,13 @@  static void blkdebug_refresh_filename(BlockDriverState *bs, QDict *options)
     }
 
     if (!force_json && bs->file->bs->exact_filename[0]) {
-        snprintf(bs->exact_filename, sizeof(bs->exact_filename),
-                 "blkdebug:%s:%s", s->config_file ?: "",
-                 bs->file->bs->exact_filename);
+        int ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename),
+                           "blkdebug:%s:%s", s->config_file ?: "",
+                           bs->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;
+        }
     }
 
     opts = qdict_new();