diff options
| author | Tobias Stoeckmann <tobias@stoeckmann.org> | 2016-09-25 21:42:09 +0200 |
|---|---|---|
| committer | Matthieu Herrb <matthieu@herrb.eu> | 2016-09-25 22:14:27 +0200 |
| commit | 8fad00b0b647ee662ce4737ca15be033b7a21714 (patch) | |
| tree | defc41b75d44d03839779cd43a72288efc3ee004 | |
| parent | b2df5bc42f64b45e44dbad61f3386bcb5ec1383d (diff) | |
Avoid OOB write in XRenderQueryFilters
The memory for filter names is reserved right after receiving the reply.
After that, filters are iterated and each individual filter name is
stored in that reserved memory.
The individual name lengths are not checked for validity, which means
that a malicious server can reserve less memory than it will write to
during each iteration.
v2: consume remaining bytes in reply buffer on error.
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>
| -rw-r--r-- | src/Filter.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/src/Filter.c b/src/Filter.c index edfa572..8d701eb 100644 --- a/src/Filter.c +++ b/src/Filter.c @@ -38,7 +38,7 @@ XRenderQueryFilters (Display *dpy, Drawable drawable) char *name; char len; int i; - unsigned long nbytes, nbytesAlias, nbytesName; + unsigned long nbytes, nbytesAlias, nbytesName, reply_left; if (!RenderHasExtension (info)) return NULL; @@ -114,6 +114,7 @@ XRenderQueryFilters (Display *dpy, Drawable drawable) * Read the filter aliases */ _XRead16Pad (dpy, filters->alias, 2 * rep.numAliases); + reply_left = 8 + rep.length - 2 * rep.numAliases;; /* * Read the filter names @@ -122,9 +123,19 @@ XRenderQueryFilters (Display *dpy, Drawable drawable) { int l; _XRead (dpy, &len, 1); + reply_left--; l = len & 0xff; + if ((unsigned long)l + 1 > nbytesName) { + _XEatDataWords(dpy, reply_left); + Xfree(filters); + UnlockDisplay (dpy); + SyncHandle (); + return NULL; + } + nbytesName -= l + 1; filters->filter[i] = name; _XRead (dpy, name, l); + reply_left -= l; name[l] = '\0'; name += l + 1; } |