[PATCH] block/vvfat.c fix leak when failure occurs

[Daniella Lee]

Function vvfat_open called function enable_write_target and init_directories,
and these functions malloc new memory for BDRVVVFATState::qcow_filename, 
BDRVVVFATState::used_clusters, and BDRVVVFATState::cluster_buff.

When the specified folder does not exist ,it may contains memory leak. 
After init_directories function is executed, the vvfat_open return -EIO, 
and bdrv_open_driver goto label open_failed, 
the program use g_free(bs->opaque) to release BDRVVVFATState struct 
without members mentioned.

command line:
qemu-system-x86_64 -hdb <vdisk qcow file>  -usb -device usb-storage,drive=fat16 
-drive file=fat:rw:fat-type=16:"<path of a host folder does not exist>",
id=fat16,format=raw,if=none

enable_write_target called:
(gdb) bt
#0  enable_write_target (bs=0x555556f9f000, errp=0x7fffffffd780) 
    at ../block/vvfat.c:3114
#1  vvfat_open (bs=0x555556f9f000, options=0x555556fa45d0, 
    flags=155650, errp=0x7fffffffd780) at ../block/vvfat.c:1236
#2  bdrv_open_driver (bs=0x555556f9f000, drv=0x555556c47920 <bdrv_vvfat>, 
    node_name=0x0, options=0x555556fa45d0, open_flags=155650, 
    errp=0x7fffffffd890) at ../block.c:1558
#3  bdrv_open_common (bs=0x555556f9f000, file=0x0, options=0x555556fa45d0,
    errp=0x7fffffffd890) at ../block.c:1852
#4  bdrv_open_inherit (filename=0x555556f73310 "fat:rw:<dirNone>", 
    reference=0x0, options=0x555556fa45d0, flags=40962, parent=0x555556f98cd0,
    child_class=0x555556b1d6a0 <child_of_bds>, child_role=19, 
    errp=0x7fffffffda90) at ../block.c:3779
#5  bdrv_open_child_bs (filename=0x555556f73310 "fat:rw:<dirNone>", 
    options=0x555556f9cfc0, bdref_key=0x555556239bb8 "file", 
    parent=0x555556f98cd0, child_class=0x555556b1d6a0 <child_of_bds>, 
    child_role=19, allow_none=true, errp=0x7fffffffda90) at ../block.c:3419
#6  bdrv_open_inherit (filename=0x555556f73310 "fat:rw:<dirNone>", 
    reference=0x0, options=0x555556f9cfc0, flags=8194, parent=0x0,
    child_class=0x0, child_role=0, errp=0x555556c98c40 <error_fatal>) 
    at ../block.c:3726
#7  bdrv_open (filename=0x555556f73310 "fat:rw:<dirNone>", reference=0x0,
    options=0x555556f757b0, flags=0, errp=0x555556c98c40 <error_fatal>) 
    at ../block.c:3872
#8  blk_new_open (filename=0x555556f73310 "fat:rw:<dirNone>", reference=0x0,
    options=0x555556f757b0, flags=0, errp=0x555556c98c40 <error_fatal>)
    at ../block/block-backend.c:436
#9  blockdev_init (file=0x555556f73310 "fat:rw:<dirNone>", 
    bs_opts=0x555556f757b0, errp=0x555556c98c40 <error_fatal>) 
    at ../blockdev.c:608
#10 drive_new (all_opts=0x555556d2b700, block_default_type=IF_IDE, 
    errp=0x555556c98c40 <error_fatal>) at ../blockdev.c:992
......

Signed-off-by: Daniella Lee <daniellalee111@gmail.com>
---
 block/vvfat.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/block/vvfat.c b/block/vvfat.c
index 05e78e3c27..454a74c5d5 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1280,7 +1280,22 @@ static int vvfat_open(BlockDriverState *bs, QDict 
*options, int flags,
     qemu_co_mutex_init(&s->lock);
 
     ret = 0;
+
+    qemu_opts_del(opts);
+    return ret;
 fail:
+    if(s->qcow_filename) {
+        g_free(s->qcow_filename);
+        s->qcow_filename = NULL;
+    }
+    if(s->cluster_buffer) {
+        g_free(s->cluster_buffer);
+        s->cluster_buffer = NULL;
+    } 
+    if(s->used_clusters) {
+        g_free(s->used_clusters);
+        s->used_clusters = NULL;
+    }
     qemu_opts_del(opts);
     return ret;
 }
-- 
2.17.1