From 7423f417827146f956df820f172d0bf80a489495 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Thu, 21 Jul 2016 13:34:46 -0600 Subject: nbd: Limit nbdflags to 16 bits Rather than asserting that nbdflags is within range, just give it the correct type to begin with :) nbdflags corresponds to the per-export portion of NBD Protocol "transmission flags", which is 16 bits in response to NBD_OPT_EXPORT_NAME and NBD_OPT_GO. Furthermore, upstream NBD has never passed the global flags to the kernel via ioctl(NBD_SET_FLAGS) (the ioctl was first introduced in NBD 2.9.22; then a latent bug in NBD 3.1 actually tried to OR the global flags with the transmission flags, with the disaster that the addition of NBD_FLAG_NO_ZEROES in 3.9 caused all earlier NBD 3.x clients to treat every export as read-only; NBD 3.10 and later intentionally clip things to 16 bits to pass only transmission flags). Qemu should follow suit, since the current two global flags (NBD_FLAG_FIXED_NEWSTYLE and NBD_FLAG_NO_ZEROES) have no impact on the kernel's behavior during transmission. CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake Message-Id: <1469129688-22848-3-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini --- qemu-nbd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'qemu-nbd.c') diff --git a/qemu-nbd.c b/qemu-nbd.c index 321f02bd15..e3571c2025 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -251,7 +251,7 @@ static void *nbd_client_thread(void *arg) { char *device = arg; off_t size; - uint32_t nbdflags; + uint16_t nbdflags; QIOChannelSocket *sioc; int fd; int ret; @@ -465,7 +465,7 @@ int main(int argc, char **argv) BlockBackend *blk; BlockDriverState *bs; off_t dev_offset = 0; - uint32_t nbdflags = 0; + uint16_t nbdflags = 0; bool disconnect = false; const char *bindto = "0.0.0.0"; const char *port = NULL; -- cgit v1.2.1