From f57e2416aaeb39c32946d282768ece7ff619b423 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 11 May 2016 16:39:40 -0600 Subject: [PATCH] nbd: Clean up ioctl handling of qemu-nbd -c The kernel ioctl() interface into NBD is limited to 'unsigned long'; we MUST pass in input with that type (and not int or size_t, as there may be platform ABIs where the wrong types promote incorrectly through var-args). Furthermore, on 32-bit platforms, the kernel is limited to a maximum export size of 2T (our BLKSIZE of 512 times a SIZE_BLOCKS constrained by 32 bit unsigned long). Signed-off-by: Eric Blake Message-Id: <1463006384-7734-8-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini --- nbd/client.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/nbd/client.c b/nbd/client.c index 5604aa9022..20e6daf70f 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -593,9 +593,15 @@ fail: #ifdef __linux__ int nbd_init(int fd, QIOChannelSocket *sioc, uint32_t flags, off_t size) { + unsigned long sectors = size / BDRV_SECTOR_SIZE; + if (size / BDRV_SECTOR_SIZE != sectors) { + LOG("Export size %lld too large for 32-bit kernel", (long long) size); + return -E2BIG; + } + TRACE("Setting NBD socket"); - if (ioctl(fd, NBD_SET_SOCK, sioc->fd) < 0) { + if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) { int serrno = errno; LOG("Failed to set NBD socket"); return -serrno; @@ -603,21 +609,25 @@ int nbd_init(int fd, QIOChannelSocket *sioc, uint32_t flags, off_t size) TRACE("Setting block size to %lu", (unsigned long)BDRV_SECTOR_SIZE); - if (ioctl(fd, NBD_SET_BLKSIZE, (size_t)BDRV_SECTOR_SIZE) < 0) { + if (ioctl(fd, NBD_SET_BLKSIZE, (unsigned long)BDRV_SECTOR_SIZE) < 0) { int serrno = errno; LOG("Failed setting NBD block size"); return -serrno; } - TRACE("Setting size to %zd block(s)", (size_t)(size / BDRV_SECTOR_SIZE)); + TRACE("Setting size to %lu block(s)", sectors); + if (size % BDRV_SECTOR_SIZE) { + TRACE("Ignoring trailing %d bytes of export", + (int) (size % BDRV_SECTOR_SIZE)); + } - if (ioctl(fd, NBD_SET_SIZE_BLOCKS, (size_t)(size / BDRV_SECTOR_SIZE)) < 0) { + if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) { int serrno = errno; LOG("Failed setting size (in blocks)"); return -serrno; } - if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) { + if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) flags) < 0) { if (errno == ENOTTY) { int read_only = (flags & NBD_FLAG_READ_ONLY) != 0; TRACE("Setting readonly attribute");