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9p: xattr: Fix crashes due to free of uninitialized value

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If the size returned from llistxattr/lgetxattr is 0, we skipped
the malloc call, leaving xattr.value uninitialized. However, this
value is later passed to `g_free` without any further checks,
causing an error. Fix that by always calling g_malloc unconditionally.
If `size` is 0, it will return NULL, which is safe to pass to g_free.

Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
This commit is contained in:
Keno Fischer 2018-06-07 12:17:22 +02:00 committed by Greg Kurz
parent ec70b956fd
commit a647502c58
1 changed files with 2 additions and 2 deletions
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4
hw/9pfs/9p.c
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@ -3256,8 +3256,8 @@ static void coroutine_fn v9fs_xattrwalk(void *opaque)
xattr_fidp->fs.xattr.len = size; xattr_fidp->fs.xattr.len = size;
xattr_fidp->fid_type = P9_FID_XATTR; xattr_fidp->fid_type = P9_FID_XATTR;
xattr_fidp->fs.xattr.xattrwalk_fid = true; xattr_fidp->fs.xattr.xattrwalk_fid = true;
if (size) {
xattr_fidp->fs.xattr.value = g_malloc0(size); xattr_fidp->fs.xattr.value = g_malloc0(size);
if (size) {
err = v9fs_co_llistxattr(pdu, &xattr_fidp->path, err = v9fs_co_llistxattr(pdu, &xattr_fidp->path,
xattr_fidp->fs.xattr.value, xattr_fidp->fs.xattr.value,
xattr_fidp->fs.xattr.len); xattr_fidp->fs.xattr.len);
@ -3289,8 +3289,8 @@ static void coroutine_fn v9fs_xattrwalk(void *opaque)
xattr_fidp->fs.xattr.len = size; xattr_fidp->fs.xattr.len = size;
xattr_fidp->fid_type = P9_FID_XATTR; xattr_fidp->fid_type = P9_FID_XATTR;
xattr_fidp->fs.xattr.xattrwalk_fid = true; xattr_fidp->fs.xattr.xattrwalk_fid = true;
if (size) {
xattr_fidp->fs.xattr.value = g_malloc0(size); xattr_fidp->fs.xattr.value = g_malloc0(size);
if (size) {
err = v9fs_co_lgetxattr(pdu, &xattr_fidp->path, err = v9fs_co_lgetxattr(pdu, &xattr_fidp->path,
&name, xattr_fidp->fs.xattr.value, &name, xattr_fidp->fs.xattr.value,
xattr_fidp->fs.xattr.len); xattr_fidp->fs.xattr.len);