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From 5d499272b95a6b890a1397e11d20937de000d31b Mon Sep 17 00:00:00 2001
From: Ray Johnston <ray.johnston@artifex.com>
Date: Wed, 22 Jul 2020 09:57:54 -0700
Subject: [PATCH] Bug 702582, CVE 2020-15900 Memory Corruption in Ghostscript
9.52
Fix the 'rsearch' calculation for the 'post' size to give the correct
size. Previous calculation would result in a size that was too large,
and could underflow to max uint32_t. Also fix 'rsearch' to return the
correct 'pre' string with empty string match.
A future change may 'undefine' this undocumented, non-standard operator
during initialization as we do with the many other non-standard internal
PostScript operators and procedures.
Upstream-Status: Backport [https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=5d499272b95a6b890a1397e11d20937de000d31b]
CVE: CVE-2020-15900
Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
---
psi/zstring.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/psi/zstring.c b/psi/zstring.c
index 33662dafa..58e1af2b3 100644
--- a/psi/zstring.c
+++ b/psi/zstring.c
@@ -142,13 +142,18 @@ search_impl(i_ctx_t *i_ctx_p, bool forward)
return 0;
found:
op->tas.type_attrs = op1->tas.type_attrs;
- op->value.bytes = ptr;
- r_set_size(op, size);
+ op->value.bytes = ptr; /* match */
+ op->tas.rsize = size; /* match */
push(2);
- op[-1] = *op1;
- r_set_size(op - 1, ptr - op[-1].value.bytes);
- op1->value.bytes = ptr + size;
- r_set_size(op1, count + (!forward ? (size - 1) : 0));
+ op[-1] = *op1; /* pre */
+ op[-3].value.bytes = ptr + size; /* post */
+ if (forward) {
+ op[-1].tas.rsize = ptr - op[-1].value.bytes; /* pre */
+ op[-3].tas.rsize = count; /* post */
+ } else {
+ op[-1].tas.rsize = count; /* pre */
+ op[-3].tas.rsize -= count + size; /* post */
+ }
make_true(op);
return 0;
}
--
2.17.1
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