diff options
| author | Ken Sharp <ken.sharp@artifex.com> | 2016-12-21 16:54:14 +0000 |
|---|---|---|
| committer | Ken Sharp <ken.sharp@artifex.com> | 2016-12-21 16:54:14 +0000 |
| commit | daf85701dab05f17e924a48a81edc9195b4a04e8 (patch) | |
| tree | f1dd5ba9587e0029edc72ac1b8d6943c0f0f0de0 | |
| parent | 2299c9a25fc9ae7b59752f1795f8b53920901c80 (diff) | |
fix crash with bad data supplied to makeimagedevice
Bug #697450 "Null pointer dereference in gx_device_finalize()"
The problem here is that the code to finalise a device unconditionally
frees the icc_struct member of the device structure. However this
particular (weird) device is not setup as a normal device, probably
because its very, very ancient. Its possible for the initialisation
of the device to abort with an error before calling gs_make_mem_device()
which is where the icc_struct member gets allocated (or set to NULL).
If that happens, then the cleanup code tries to free the device, which
calls finalize() which tries to free a garbage pointer.
Setting the device memory to 0x00 after we allocate it means that the
icc_struct member will be NULL< and our memory manager allows for that
happily enough, which avoids the problem.
| -rw-r--r-- | base/gsdevmem.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/base/gsdevmem.c b/base/gsdevmem.c index 97b9cf42b..fe75bccb5 100644 --- a/base/gsdevmem.c +++ b/base/gsdevmem.c @@ -225,6 +225,18 @@ gs_makewordimagedevice(gx_device ** pnew_dev, const gs_matrix * pmat, if (pnew == 0) return_error(gs_error_VMerror); + + /* Bug #697450 "Null pointer dereference in gx_device_finalize()" + * If we have incorrect data passed to gs_initialise_wordimagedevice() then the + * initialisation will fail, crucially it will fail *before* it calls + * gs_make_mem_device() which initialises the device. This means that the + * icc_struct member will be uninitialsed, but the device finalise method + * will unconditionally free that memory. Since its a garbage pointer, bad things happen. + * Apparently we do still need makeimagedevice to be available from + * PostScript, so in here just zero the device memory, which means that + * the finalise routine won't have a problem. + */ + memset(pnew, 0x00, st_device_memory.ssize); code = gs_initialize_wordimagedevice(pnew, pmat, width, height, colors, num_colors, word_oriented, page_device, mem); |
