23.06.2020 00:03, Eric Blake wrote:
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
Oh, I remember myself checking snprintf spec when reviewing this, but
still I missed this thing :(
Reported-by: Max Reitz <mre...@redhat.com>
Signed-off-by: Eric Blake <ebl...@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
block/nbd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/nbd.c b/block/nbd.c
index eed160c5cda1..8301fcac0589 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -2009,7 +2009,7 @@ 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';
}
Hmm, interesting, that in case of len=0 (no one branch was executed from
previous
if-else-if, which seems possible) we do nothing. Shouldn't this if actually be
if (!len || len >= sizeof(bs->exact_filename)) {
/* Name is too long or we have nothing to report */
bs->exact_filename[0] = '\0';
}
Probably not, as bdrv_refresh_filename() does it anyway prior to calling
drv->bdrv_refresh_filename().
--
Best regards,
Vladimir
