From 5d499272b95a6b890a1397e11d20937de000d31b Mon Sep 17 00:00:00 2001 From: Ray Johnston 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 --- 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