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[Qemu-devel] [PATCH] block/vmdk: Report failures in vmdk_read_cid()
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH] block/vmdk: Report failures in vmdk_read_cid() |
Date: |
Sun, 9 Jul 2017 18:06:14 +0100 |
The function vmdk_read_cid() can fail if the read on the underlying
block device fails, or if there's a format error in the VMDK file.
However its API doesn't provide a mechanism to report these errors,
and in some cases we were returning a CID of 0 and in some cases a
CID of 0xffffffff, either of which might potentially be valid values.
Change the function to return 0 on success or a negative errno, and
return the CID via a uint32_t* argument. Update the callsites to
handle and propagate the error appropriately.
This fixes in passing a Coverity-spotted issue (CID 1350038) where
we weren't checking the return value from sscanf().
Signed-off-by: Peter Maydell <address@hidden>
---
block/vmdk.c | 44 ++++++++++++++++++++++++++++++++------------
1 file changed, 32 insertions(+), 12 deletions(-)
diff --git a/block/vmdk.c b/block/vmdk.c
index 55581b03fe..0c9949fc0c 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -242,10 +242,11 @@ static void vmdk_free_last_extent(BlockDriverState *bs)
s->extents = g_renew(VmdkExtent, s->extents, s->num_extents);
}
-static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent)
+/* Return -ve errno, or 0 on success and write CID into *pcid. */
+static int vmdk_read_cid(BlockDriverState *bs, int parent, uint32_t *pcid)
{
char *desc;
- uint32_t cid = 0xffffffff;
+ uint32_t cid;
const char *p_name, *cid_str;
size_t cid_str_size;
BDRVVmdkState *s = bs->opaque;
@@ -254,8 +255,7 @@ static uint32_t vmdk_read_cid(BlockDriverState *bs, int
parent)
desc = g_malloc0(DESC_SIZE);
ret = bdrv_pread(bs->file, s->desc_offset, desc, DESC_SIZE);
if (ret < 0) {
- g_free(desc);
- return 0;
+ goto out;
}
if (parent) {
@@ -268,13 +268,21 @@ static uint32_t vmdk_read_cid(BlockDriverState *bs, int
parent)
desc[DESC_SIZE - 1] = '\0';
p_name = strstr(desc, cid_str);
- if (p_name != NULL) {
- p_name += cid_str_size;
- sscanf(p_name, "%" SCNx32, &cid);
+ if (p_name == NULL) {
+ ret = -EINVAL;
+ goto out;
}
+ p_name += cid_str_size;
+ if (sscanf(p_name, "%" SCNx32, &cid) != 1) {
+ ret = -EINVAL;
+ goto out;
+ }
+ *pcid = cid;
+ ret = 0;
+out:
g_free(desc);
- return cid;
+ return ret;
}
static int vmdk_write_cid(BlockDriverState *bs, uint32_t cid)
@@ -322,7 +330,10 @@ static int vmdk_is_cid_valid(BlockDriverState *bs)
if (!s->cid_checked && bs->backing) {
BlockDriverState *p_bs = bs->backing->bs;
- cur_pcid = vmdk_read_cid(p_bs, 0);
+ if (vmdk_read_cid(p_bs, 0, &cur_pcid) != 0) {
+ /* read failure: report as not valid */
+ return 0;
+ }
if (s->parent_cid != cur_pcid) {
/* CID not valid */
return 0;
@@ -975,8 +986,14 @@ static int vmdk_open(BlockDriverState *bs, QDict *options,
int flags,
if (ret) {
goto fail;
}
- s->cid = vmdk_read_cid(bs, 0);
- s->parent_cid = vmdk_read_cid(bs, 1);
+ ret = vmdk_read_cid(bs, 0, &s->cid);
+ if (ret) {
+ goto fail;
+ }
+ ret = vmdk_read_cid(bs, 1, &s->parent_cid);
+ if (ret) {
+ goto fail;
+ }
qemu_co_mutex_init(&s->lock);
/* Disable migration when VMDK images are used */
@@ -2007,8 +2024,11 @@ static int vmdk_create(const char *filename, QemuOpts
*opts, Error **errp)
ret = -EINVAL;
goto exit;
}
- parent_cid = vmdk_read_cid(blk_bs(blk), 0);
+ ret = vmdk_read_cid(blk_bs(blk), 0, &parent_cid);
blk_unref(blk);
+ if (ret) {
+ goto exit;
+ }
snprintf(parent_desc_line, BUF_SIZE,
"parentFileNameHint=\"%s\"", backing_file);
}
--
2.11.0
- [Qemu-devel] [PATCH] block/vmdk: Report failures in vmdk_read_cid(),
Peter Maydell <=