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Aw c'mon. I'm being driven mad by plenty of other things. I don't

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need this.

Consider the following code:

	case 'O':
		output_filename = malloc(strlen(arg)+4);
		strcpy(output_filename, arg);
		strcat(output_filename, ".tmp");
		real_output_filename = arg;
		return;

The idea here is to malloc() a buffer big enough to hold the name of
a supplied file name, plus ".tmp". So we malloc() 'size of filename'
bytes plus 4, right? Wrong! ".tmp" is _FIVE_ bytes long! There's a
traling '\0' which strcat() gleefully tacks on _outside_ the bounds
of the buffer. Result: program corrupts own memory. Program SEGVs at
seemingly random times. Bill not like random SEGVs. Bill smash.

Know how I found this? I've been trying to bootstrap -current on my
2.1.0-RELEASE machine at work and I couldn't seem to get libc.a built
because the linker would intermittently blow chunks while executing
things like 'ld -O foo.o -X -r foo.o'. Since this is an initial
bootstrap version of ld, it was linked against the 2.1.0 libc, who's
malloc() behaves differently than that in -current.

Presumeably ld -O doesn't blow up in -current, otherwise someone would
have spotted this already. I don't know if this is a bug or a feature.

Anyway. I'm changing the strlen(arg)+4 to strlen(arg)+5. Bah.
This commit is contained in:
Bill Paul 1996-06-08 04:52:57 +00:00
parent 4c0c227d97
commit a13bb127d2
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
gnu/usr.bin/ld/ld.c
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@ -32,7 +32,7 @@ static char sccsid[] = "@(#)ld.c 6.10 (Berkeley) 5/22/91";
Set, indirect, and warning symbol features added by Randy Smith. */
/*
* $Id: ld.c,v 1.32 1996/04/24 23:31:08 jdp Exp $
* $Id: ld.c,v 1.33 1996/05/28 16:17:48 phk Exp $
*/
/* Define how to initialize system-dependent header fields. */
@ -700,7 +700,7 @@ decode_option(swt, arg)
return;
case 'O':
output_filename = malloc(strlen(arg)+4);
output_filename = malloc(strlen(arg)+5);
strcpy(output_filename, arg);
strcat(output_filename, ".tmp");
real_output_filename = arg;