Date: Mon, 2 Aug 2010 09:13:09 +0000 (UTC) From: Jaakko Heinonen <jh@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r210745 - stable/8/lib/libc/stdlib Message-ID: <201008020913.o729D9Ob075208@svn.freebsd.org>
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Author: jh Date: Mon Aug 2 09:13:09 2010 New Revision: 210745 URL: http://svn.freebsd.org/changeset/base/210745 Log: MFC r204636: In reallocf(3), free the memory only when size != 0. Otherwise, when the System V compatibility option (malloc "V" flag) is in effect a zero sized reallocf() could cause a double free. PR: bin/141753 Modified: stable/8/lib/libc/stdlib/reallocf.c Directory Properties: stable/8/lib/libc/ (props changed) stable/8/lib/libc/stdtime/ (props changed) stable/8/lib/libc/sys/ (props changed) Modified: stable/8/lib/libc/stdlib/reallocf.c ============================================================================== --- stable/8/lib/libc/stdlib/reallocf.c Mon Aug 2 09:03:31 2010 (r210744) +++ stable/8/lib/libc/stdlib/reallocf.c Mon Aug 2 09:13:09 2010 (r210745) @@ -35,7 +35,14 @@ reallocf(void *ptr, size_t size) void *nptr; nptr = realloc(ptr, size); - if (!nptr && ptr) + + /* + * When the System V compatibility option (malloc "V" flag) is + * in effect, realloc(ptr, 0) frees the memory and returns NULL. + * So, to avoid double free, call free() only when size != 0. + * realloc(ptr, 0) can't fail when ptr != NULL. + */ + if (!nptr && ptr && size != 0) free(ptr); return (nptr); }
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