9front - general discussion about 9front
 help / color / mirror / Atom feed
* [9front] acme: fix leaking memory allocated by getenv("font")
@ 2021-11-06  0:05 igor
  0 siblings, 0 replies; only message in thread
From: igor @ 2021-11-06  0:05 UTC (permalink / raw)
  To: 9front; +Cc: igor

[-- Attachment #1: Type: text/plain, Size: 3470 bytes --]

The attached patch fixes a memory leak that occurs on a code
path where the acme font is retrieved via `getenv("font")`.

It is a small leak. Its presence is still annoying as it
pollutes leak(1) output for acme.

I am posting the patch here first in case there is review feedback.

If no one objects I will push it over the weekend.

Cheers,
Igor

<snip>
From: Igor Böhm <igor@9lab.org>
Date: Fri, 05 Nov 2021 23:51:55 +0000
Subject: [PATCH] acme: fix leaking memory allocated by getenv("font")


If the font chosen for acme is retrieved via `getenv("font")` its
memory is leaked:

<snip>
	if(fontnames[0] == nil)
		fontnames[0] = getenv("font");
		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> getenv(…) mallocs memory

	if(fontnames[0] == nil)
		fontnames[0] = "/lib/font/bit/vga/unicode.font";
	if(access(fontnames[0], 0) < 0){
		fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
		exits("font open");
	}
	if(fontnames[1] == nil)
		fontnames[1] = fontnames[0];
	fontnames[0] = estrdup(fontnames[0]);
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> if the `getenv("font")` path was taken above, this assignment
> will leak its memory.
</snap>

The following leak/acid session demonstrates the issue:

<snip>
cpu% leak -s 212252
src(0x002000cb); // 1
cpu% acid 212252
/proc/212252/text:amd64 plan 9 executable
/sys/lib/acid/port
/sys/lib/acid/amd64
acid: src(0x002000cb)
/sys/src/cmd/acme/acme.c:107
 102			fprint(2, "usage: acme [-aib] [-c ncol] [-f font] [-F fixedfont] [-l loadfile | file...]\n");
 103			exits("usage");
 104		}ARGEND
 105
 106		if(fontnames[0] == nil)
>107			fontnames[0] = getenv("font");
 108		if(fontnames[0] == nil)
 109			fontnames[0] = "/lib/font/bit/vga/unicode.font";
 110		if(access(fontnames[0], 0) < 0){
 111			fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
 112			exits("font open");
acid:
</snap>

The fix tries to first check if a font has been set via
command line options in which case the font string is
malloced via estrdup(…).

If no font has been selected on the command line getenv("font")
is used. If no getenv("font") var is found we malloc a default
font via estrdup(…).

<snip>
	if(fontnames[0] != nil)
		fontnames[0] = estrdup(fontnames[0]);
	else
		if((fontnames[0] = getenv("font")) == nil)
			fontnames[0] = estrdup("/lib/font/bit/vga/unicode.font");
	if(access(fontnames[0], 0) < 0){
		fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
		exits("font open");
	}
	if(fontnames[1] == nil)
		fontnames[1] = fontnames[0];
	fontnames[1] = estrdup(fontnames[1]);
</snap>

This resolves the memory leak and indeed leak(1) will not report
any leaks ☺
---
diff 775608db7c004aca265474adb3e081f676b3b12a cb2f16fd1b18ff6bf12b594d129b8ff54423cb58
--- a/sys/src/cmd/acme/acme.c	Fri Nov  5 00:11:56 2021
+++ b/sys/src/cmd/acme/acme.c	Sat Nov  6 00:51:55 2021
@@ -103,17 +103,17 @@
 		exits("usage");
 	}ARGEND
 
-	if(fontnames[0] == nil)
-		fontnames[0] = getenv("font");
-	if(fontnames[0] == nil)
-		fontnames[0] = "/lib/font/bit/vga/unicode.font";
+	if(fontnames[0] != nil)
+		fontnames[0] = estrdup(fontnames[0]);
+	else
+		if((fontnames[0] = getenv("font")) == nil)
+			fontnames[0] = estrdup("/lib/font/bit/vga/unicode.font");		
 	if(access(fontnames[0], 0) < 0){
 		fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
 		exits("font open");
 	}
 	if(fontnames[1] == nil)
 		fontnames[1] = fontnames[0];
-	fontnames[0] = estrdup(fontnames[0]);
 	fontnames[1] = estrdup(fontnames[1]);
 
 	quotefmtinstall();
</snap>

[-- Attachment #2: acme.getenv.font.patch --]
[-- Type: text/plain, Size: 3105 bytes --]

From: Igor Böhm <igor@9lab.org>
Date: Fri, 05 Nov 2021 23:51:55 +0000
Subject: [PATCH] acme: fix leaking memory allocated by getenv("font")


If the font chosen for acme is retrieved via `getenv("font")` its
memory is leaked:

<snip>
	if(fontnames[0] == nil)
		fontnames[0] = getenv("font");
		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> getenv(…) mallocs memory

	if(fontnames[0] == nil)
		fontnames[0] = "/lib/font/bit/vga/unicode.font";
	if(access(fontnames[0], 0) < 0){
		fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
		exits("font open");
	}
	if(fontnames[1] == nil)
		fontnames[1] = fontnames[0];
	fontnames[0] = estrdup(fontnames[0]);
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> if the `getenv("font")` path was taken above, this assignment
> will leak its memory.
</snap>

The following leak/acid session demonstrates the issue:

<snip>
cpu% leak -s 212252
src(0x002000cb); // 1
cpu% acid 212252
/proc/212252/text:amd64 plan 9 executable
/sys/lib/acid/port
/sys/lib/acid/amd64
acid: src(0x002000cb)
/sys/src/cmd/acme/acme.c:107
 102			fprint(2, "usage: acme [-aib] [-c ncol] [-f font] [-F fixedfont] [-l loadfile | file...]\n");
 103			exits("usage");
 104		}ARGEND
 105
 106		if(fontnames[0] == nil)
>107			fontnames[0] = getenv("font");
 108		if(fontnames[0] == nil)
 109			fontnames[0] = "/lib/font/bit/vga/unicode.font";
 110		if(access(fontnames[0], 0) < 0){
 111			fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
 112			exits("font open");
acid:
</snap>

The fix tries to first check if a font has been set via
command line options in which case the font string is
malloced via estrdup(…).

If no font has been selected on the command line getenv("font")
is used. If no getenv("font") var is found we malloc a default
font via estrdup(…).

<snip>
	if(fontnames[0] != nil)
		fontnames[0] = estrdup(fontnames[0]);
	else
		if((fontnames[0] = getenv("font")) == nil)
			fontnames[0] = estrdup("/lib/font/bit/vga/unicode.font");
	if(access(fontnames[0], 0) < 0){
		fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
		exits("font open");
	}
	if(fontnames[1] == nil)
		fontnames[1] = fontnames[0];
	fontnames[1] = estrdup(fontnames[1]);
</snap>

This resolves the memory leak and indeed leak(1) will not report
any leaks ☺
---
diff 775608db7c004aca265474adb3e081f676b3b12a cb2f16fd1b18ff6bf12b594d129b8ff54423cb58
--- a/sys/src/cmd/acme/acme.c	Fri Nov  5 00:11:56 2021
+++ b/sys/src/cmd/acme/acme.c	Sat Nov  6 00:51:55 2021
@@ -103,17 +103,17 @@
 		exits("usage");
 	}ARGEND
 
-	if(fontnames[0] == nil)
-		fontnames[0] = getenv("font");
-	if(fontnames[0] == nil)
-		fontnames[0] = "/lib/font/bit/vga/unicode.font";
+	if(fontnames[0] != nil)
+		fontnames[0] = estrdup(fontnames[0]);
+	else
+		if((fontnames[0] = getenv("font")) == nil)
+			fontnames[0] = estrdup("/lib/font/bit/vga/unicode.font");		
 	if(access(fontnames[0], 0) < 0){
 		fprint(2, "acme: can't access %s: %r\n", fontnames[0]);
 		exits("font open");
 	}
 	if(fontnames[1] == nil)
 		fontnames[1] = fontnames[0];
-	fontnames[0] = estrdup(fontnames[0]);
 	fontnames[1] = estrdup(fontnames[1]);
 
 	quotefmtinstall();

^ permalink raw reply	[flat|nested] only message in thread

only message in thread, other threads:[~2021-11-06  0:26 UTC | newest]

Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-06  0:05 [9front] acme: fix leaking memory allocated by getenv("font") igor

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).