[nasm:nasm-2.15.xx] parser: when flattening an eop, must preserve any data buffer

[nasm-bot for H. Peter Anvin (Intel)]

Commit-ID:  6ac6ac57e3d01ea8ed4ea47706eb724b59176461
Gitweb:     http://repo.or.cz/w/nasm.git?a=commitdiff;h=6ac6ac57e3d01ea8ed4ea47706eb724b59176461
Author:     H. Peter Anvin (Intel) <hpa at zytor.com>
AuthorDate: Thu, 30 Jul 2020 15:46:12 -0700
Committer:  H. Peter Anvin (Intel) <hpa at zytor.com>
CommitDate: Thu, 30 Jul 2020 15:48:45 -0700

parser: when flattening an eop, must preserve any data buffer

An eop may have a data buffer associated with it as part of the same
memory allocation. Therefore, we need to move "subexpr" up instead of
merging it into "eop".

This *partially* resolves BR 3392707, but that test case still
triggers a violation when using -gcv8.

Reported-by: Suhwan <prada960808 at gmail.com>
Signed-off-by: H. Peter Anvin (Intel) <hpa at zytor.com>


---
 asm/parser.c                    | 16 +++++++++++-----
 test/{dup.asm => br3392707.asm} | 21 +++------------------
 2 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/asm/parser.c b/asm/parser.c
index dbd2240c..584e40c9 100644
--- a/asm/parser.c
+++ b/asm/parser.c
@@ -458,11 +458,17 @@ static int parse_eops(extop **result, bool critical, int elem)
                 /* Subexpression is empty */
                 eop->type = EOT_NOTHING;
             } else if (!subexpr->next) {
-                /* Subexpression is a single element, flatten */
-                eop->val   = subexpr->val;
-                eop->type  = subexpr->type;
-                eop->dup  *= subexpr->dup;
-                nasm_free(subexpr);
+                /*
+                 * Subexpression is a single element, flatten.
+                 * Note that if subexpr has an allocated buffer associated
+                 * with it, freeing it would free the buffer, too, so
+                 * we need to move subexpr up, not eop down.
+                 */
+                if (!subexpr->elem)
+                    subexpr->elem = eop->elem;
+                subexpr->dup *= eop->dup;
+                nasm_free(eop);
+                eop = subexpr;
             } else {
                 eop->type = EOT_EXTOP;
             }
diff --git a/test/dup.asm b/test/br3392707.asm
similarity index 54%
copy from test/dup.asm
copy to test/br3392707.asm
index 62785628..6e84c5b4 100644
--- a/test/dup.asm
+++ b/test/br3392707.asm
@@ -3,7 +3,7 @@
 	db 33
 	db (44)
 ;	db (44,55)	-- error
-	db %(44,55)
+	db %(44.55)
 	db %('XX','YY')
 	db ('AA')
 	db %('BB')
@@ -12,25 +12,10 @@
 	db 6 dup (33, 34)
 	db 6 dup (33, 34), 35
 	db 7 dup (99)
-	db 7 dup dword (?, word ?,?)
+	db 7 dup (?,?)
 	dw byte (?,44)
 
-	dw 3 dup (0xcc, 4 dup byte ('PQR'), ?), 0xabcd
+	dw 0xcc, 4 dup byte ('PQR'), ?, 0xabcd
 
 	dd 16 dup (0xaaaa, ?, 0xbbbbbb)
 	dd 64 dup (?)
-
-	resb 1
-	resb 2
-	resb 4
-	resb 8
-
-	resw 1
-	resw 2
-	resw 4
-	resw 8
-
-	resq 1
-	resq 2
-	resq 4
-	resq 8