Date: Sat, 28 Aug 2010 06:33:01 +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-7@freebsd.org Subject: svn commit: r211919 - stable/7/lib/libc/stdlib Message-ID: <201008280633.o7S6X17Y021339@svn.freebsd.org>
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Author: jh Date: Sat Aug 28 06:33:01 2010 New Revision: 211919 URL: http://svn.freebsd.org/changeset/base/211919 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/7/lib/libc/stdlib/reallocf.c Directory Properties: stable/7/lib/libc/ (props changed) stable/7/lib/libc/stdtime/ (props changed) Modified: stable/7/lib/libc/stdlib/reallocf.c ============================================================================== --- stable/7/lib/libc/stdlib/reallocf.c Sat Aug 28 06:31:15 2010 (r211918) +++ stable/7/lib/libc/stdlib/reallocf.c Sat Aug 28 06:33:01 2010 (r211919) @@ -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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