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

[patchbot@xxxxxxx]

commit e05274ac9a75e58ffe75cf083ac821bb6079ccee
Author:     Max Reitz <mreitz@xxxxxxxxxx>
AuthorDate: Tue Jun 13 19:20:05 2017 +0200
Commit:     Anthony PERARD <anthony.perard@xxxxxxxxxx>
CommitDate: Mon Jul 9 12:37:56 2018 +0100

    blkdebug: Catch bs->exact_filename overflow
    
    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@xxxxxxxxxx
    Reported-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
    Signed-off-by: Max Reitz <mreitz@xxxxxxxxxx>
    Message-id: 20170613172006.19685-2-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 de81d72d3d13a19edf4d461be3b0f5a877be0234)
---
 block/blkdebug.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 4127571454..a71c6535cf 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -702,9 +702,13 @@ 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();
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.9

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