On Thu, 31 May 2018 21:25:58 -0400 Keno Fischer <k...@juliacomputing.com> wrote:
> If the size returned from llistxattr 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 Ouch, good catch. > error. Fix that by always calling g_malloc unconditionally. If > `size` is 0, it will return a pointer that is safe to pass to g_free, > likely NULL. > "Allocates n_bytes bytes of memory, initialized to 0's. If n_bytes is 0 it returns NULL." https://developer.gnome.org/glib/unstable/glib-Memory-Allocation.html#g-malloc The fix is good, but it seems the same can also happen if v9fs_co_lgetxattr() returns 0 a few lines below. Can you check this out and fix it if needed ? > Signed-off-by: Keno Fischer <k...@juliacomputing.com> > --- > > Changes since v1: New patch > > hw/9pfs/9p.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index d74302d..b80db65 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -3256,8 +3256,8 @@ static void coroutine_fn v9fs_xattrwalk(void *opaque) > xattr_fidp->fs.xattr.len = size; > xattr_fidp->fid_type = P9_FID_XATTR; > xattr_fidp->fs.xattr.xattrwalk_fid = true; > + xattr_fidp->fs.xattr.value = g_malloc0(size); > if (size) { > - xattr_fidp->fs.xattr.value = g_malloc0(size); > err = v9fs_co_llistxattr(pdu, &xattr_fidp->path, > xattr_fidp->fs.xattr.value, > xattr_fidp->fs.xattr.len);