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authorEric Blake <eblake@redhat.com>2019-01-17 13:36:42 -0600
committerEric Blake <eblake@redhat.com>2019-01-21 15:49:51 -0600
commit7596bbb390838359e4789996f349bda0cad56b0e (patch)
treec42691a88bb5a3556682937e92fa53326e68bedb /nbd
parent4485936b6de20afa38138e9d1e8ffed88cf0be73 (diff)
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nbd/server: Hoist length check to qmp_nbd_server_add
We only had two callers to nbd_export_new; qemu-nbd.c always passed a valid offset/length pair (because it already checked the file length, to ensure that offset was in bounds), while blockdev-nbd.c always passed 0/-1. Then nbd_export_new reduces the size to a multiple of BDRV_SECTOR_SIZE (can only happen when offset is not sector-aligned, since bdrv_getlength() currently rounds up) (someday, it would be nice to have byte-accurate lengths - but not today). However, I'm finding it easier to work with the code if we are consistent on having both callers pass in a valid length, and just assert that things are sane in nbd_export_new, meaning that no negative values were passed, and that offset+size does not exceed 63 bits (as that really is a fundamental limit to later operations, whether we use off_t or uint64_t). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20190117193658.16413-6-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Diffstat (limited to 'nbd')
-rw-r--r--nbd/server.c10
1 files changed, 3 insertions, 7 deletions
diff --git a/nbd/server.c b/nbd/server.c
index 6b13601..51ee809 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1495,17 +1495,13 @@ NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
+ assert(dev_offset >= 0 && dev_offset <= INT64_MAX);
exp->dev_offset = dev_offset;
exp->name = g_strdup(name);
exp->description = g_strdup(description);
exp->nbdflags = nbdflags;
- exp->size = size < 0 ? blk_getlength(blk) : size;
- if (exp->size < 0) {
- error_setg_errno(errp, -exp->size,
- "Failed to determine the NBD export's length");
- goto fail;
- }
- exp->size -= exp->size % BDRV_SECTOR_SIZE;
+ assert(size >= 0 && size <= INT64_MAX - dev_offset);
+ exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
if (bitmap) {
BdrvDirtyBitmap *bm = NULL;