diff mbox series

[v3,2/5] 9p: xattr: Fix crashes due to free of uninitialized value

Message ID cb0205334adbf17155eeb172c4885e8f295fe5cc.1527973524.git.keno@juliacomputing.com
State New
Headers show
Series Prepratory cleanup for 9p darwin support | expand

Commit Message

Keno Fischer June 2, 2018, 9:29 p.m. UTC 
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>
---

Changes since v2:
 * Fix another instance of the problematic pattern later in the same function.

 hw/9pfs/9p.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index d74302d..4386d69 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);
@@ -3289,8 +3289,8 @@  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_lgetxattr(pdu, &xattr_fidp->path,
                                     &name, xattr_fidp->fs.xattr.value,
                                     xattr_fidp->fs.xattr.len);