Date: Tue, 15 Oct 2013 13:32:02 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r256537 - head/lib/libc/gen Message-ID: <201310151332.r9FDW2NU027808@svn.freebsd.org>
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Author: glebius Date: Tue Oct 15 13:32:01 2013 New Revision: 256537 URL: http://svnweb.freebsd.org/changeset/base/256537 Log: Make getutxent(3) more robust against bad utx.log files. Whenever we read zeroes, don't stop processing the file, but read until its end or valid data. In collaboration with: ed Modified: head/lib/libc/gen/getutxent.c Modified: head/lib/libc/gen/getutxent.c ============================================================================== --- head/lib/libc/gen/getutxent.c Tue Oct 15 13:24:10 2013 (r256536) +++ head/lib/libc/gen/getutxent.c Tue Oct 15 13:32:01 2013 (r256537) @@ -122,9 +122,20 @@ getfutxent(struct futx *fu) if (udb == UTXDB_LOG) { uint16_t len; +retry: if (fread(&len, sizeof(len), 1, uf) != 1) return (-1); len = be16toh(len); + if (len == 0) { + /* + * XXX: Though zero-size records are valid in theory, + * they can never occur in practice. Zero-size records + * indicate file corruption. Seek one byte forward, to + * see if we can find a record there. + */ + ungetc('\0', uf); + goto retry; + } if (len > sizeof *fu) { /* Forward compatibility. */ if (fread(fu, sizeof(*fu), 1, uf) != 1)
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