Debian Bug report logs - #903153
nasm does not handle rdf2 output correctly due to incorrect use of pure_func

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Message #5 received at [email protected] (full text, mbox, reply):

From: Petr Vandrovec <[email protected]>

To: <[email protected]>

Cc: <[email protected]>, <[email protected]>, <[email protected]>

Subject: nasm does not handle rdf2 output correctly due to incorrect use of pure_func

Date: Fri, 6 Jul 2018 23:08:12 -0700

Package: nasm
Version: 2.13.03-1

Hi,
  when I tried to switch to new nasm for one of our projects,
nasm started panicking;

nasm: panic: rdf segment numbers not allocated as expected (0,0,0)

nasm code in question calls seg_alloc 3 times:

    segtext = seg_alloc();
    segdata = seg_alloc();
    segbss = seg_alloc();
    if (segtext != 0 || segdata != 2 || segbss != 4)
        nasm_panic(0,
              "rdf segment numbers not allocated as expected (%d,%d,%d)",
              segtext, segdata, segbss);

and seg_alloc returns consecutive even integers, so it should never
happen that all three would be zeroes.

Except that seg_alloc() is marked as pure_func, and so new gcc figures
out that seg_alloc() returns constant, and so it can call it just once,
and then assign returned value to all three variables :-(

Simple fix below solves the problem.

Petr

Signed-off-by: Petr Vandrovec <[email protected]>

--- nasm-2.13.03/include/nasmlib.h	2018-02-07 13:40:15.000000000 -0800
+++ nasm-2.13.03.patched/include/nasmlib.h	2018-07-06 22:59:37.595561715 -0700
@@ -192,7 +192,7 @@
  * seg_alloc: allocate a hitherto unused segment number.
  */
 void pure_func seg_init(void);
-int32_t pure_func seg_alloc(void);
+int32_t seg_alloc(void);
 
 /*
  * many output formats will be able to make use of this: a standard

Message #10 received at [email protected] (full text, mbox, reply):

From: Jordan Justen <[email protected]>

To: [email protected]

Subject: RE: nasm does not handle rdf2 output correctly due to incorrect use of pure_func

Date: Tue, 12 Feb 2019 01:41:25 -0800

Hi. Does the 2.14-1 release fix this? I see that upstream included at
patch exactly like yours:

commit 9f45a77f46829e666b35530939b9237cf978d4dc
Author: Cyrill Gorcunov <[email protected]>
Date:   Sat Feb 10 00:40:46 2018 +0300

    nasmlib: Drop pure_func attrib from seg_alloc

This patch should have been included is 2.14-1.

Thanks,

-Jordan

Message #15 received at [email protected] (full text, mbox, reply):

From: Παναγιώτης Μπίκος <[email protected]>

To: "[email protected]" <[email protected]>

Subject: Re: RE: nasm does not handle rdf2 output correctly due to incorrect use of pure_func

Date: Sun, 17 Nov 2019 19:50:23 +0000

Issue persists in nasm 2.14-1 (Debian 10.2 Stable)


pbikos@dev:/home/large/code/osdev$ cat main.asm

section .text

pbikos@dev:/home/large/code/osdev$ nasm -f rdf main.asm
main.asm:panic: rdf segment numbers not allocated as expected (2,4,6)
pbikos@dev:/home/large/code/osdev$ nasm -v
NASM version 2.14

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