|
 |
e76b7b9 |
From daf85701dab05f17e924a48a81edc9195b4a04e8 Mon Sep 17 00:00:00 2001
|
|
|
e76b7b9 |
From: Ken Sharp <ken.sharp@artifex.com>
|
|
|
e76b7b9 |
Date: Wed, 21 Dec 2016 16:54:14 +0000
|
|
|
e76b7b9 |
Subject: [PATCH] fix crash with bad data supplied to makeimagedevice
|
|
|
e76b7b9 |
|
|
|
e76b7b9 |
Bug #697450 "Null pointer dereference in gx_device_finalize()"
|
|
|
e76b7b9 |
|
|
|
e76b7b9 |
The problem here is that the code to finalise a device unconditionally
|
|
|
e76b7b9 |
frees the icc_struct member of the device structure. However this
|
|
|
e76b7b9 |
particular (weird) device is not setup as a normal device, probably
|
|
|
e76b7b9 |
because its very, very ancient. Its possible for the initialisation
|
|
|
e76b7b9 |
of the device to abort with an error before calling gs_make_mem_device()
|
|
|
e76b7b9 |
which is where the icc_struct member gets allocated (or set to NULL).
|
|
|
e76b7b9 |
|
|
|
e76b7b9 |
If that happens, then the cleanup code tries to free the device, which
|
|
|
e76b7b9 |
calls finalize() which tries to free a garbage pointer.
|
|
|
e76b7b9 |
|
|
|
e76b7b9 |
Setting the device memory to 0x00 after we allocate it means that the
|
|
|
e76b7b9 |
icc_struct member will be NULL< and our memory manager allows for that
|
|
|
e76b7b9 |
happily enough, which avoids the problem.
|
|
|
e76b7b9 |
---
|
|
|
e76b7b9 |
base/gsdevmem.c | 12 ++++++++++++
|
|
|
e76b7b9 |
1 file changed, 12 insertions(+)
|
|
|
e76b7b9 |
|
|
|
e76b7b9 |
diff --git a/base/gsdevmem.c b/base/gsdevmem.c
|
|
|
e76b7b9 |
index 97b9cf4..fe75bcc 100644
|
|
|
e76b7b9 |
--- a/base/gsdevmem.c
|
|
|
e76b7b9 |
+++ b/base/gsdevmem.c
|
|
|
e76b7b9 |
@@ -225,6 +225,18 @@ gs_makewordimagedevice(gx_device ** pnew_dev, const gs_matrix * pmat,
|
|
|
e76b7b9 |
|
|
|
e76b7b9 |
if (pnew == 0)
|
|
|
e76b7b9 |
return_error(gs_error_VMerror);
|
|
|
e76b7b9 |
+
|
|
|
e76b7b9 |
+ /* Bug #697450 "Null pointer dereference in gx_device_finalize()"
|
|
|
e76b7b9 |
+ * If we have incorrect data passed to gs_initialise_wordimagedevice() then the
|
|
|
e76b7b9 |
+ * initialisation will fail, crucially it will fail *before* it calls
|
|
|
e76b7b9 |
+ * gs_make_mem_device() which initialises the device. This means that the
|
|
|
e76b7b9 |
+ * icc_struct member will be uninitialsed, but the device finalise method
|
|
|
e76b7b9 |
+ * will unconditionally free that memory. Since its a garbage pointer, bad things happen.
|
|
|
e76b7b9 |
+ * Apparently we do still need makeimagedevice to be available from
|
|
|
e76b7b9 |
+ * PostScript, so in here just zero the device memory, which means that
|
|
|
e76b7b9 |
+ * the finalise routine won't have a problem.
|
|
|
e76b7b9 |
+ */
|
|
|
e76b7b9 |
+ memset(pnew, 0x00, st_device_memory.ssize);
|
|
|
e76b7b9 |
code = gs_initialize_wordimagedevice(pnew, pmat, width, height,
|
|
|
e76b7b9 |
colors, num_colors, word_oriented,
|
|
|
e76b7b9 |
page_device, mem);
|
|
|
e76b7b9 |
--
|
|
|
e76b7b9 |
2.9.3
|
|
|
e76b7b9 |
|