Date: Tue, 24 Aug 2010 15:16:13 +0200 (CEST) From: Martin Beran <mb@tns.cz> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/149936: [patch] wrong handling of decompression utilities in libmagic Message-ID: <20100824131613.DC8502A6826@mb.tns.cz> Resent-Message-ID: <201008241340.o7ODe2eT092224@freefall.freebsd.org>
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>Number: 149936 >Category: bin >Synopsis: [patch] wrong handling of decompression utilities in libmagic >Confidential: no >Severity: non-critical >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Aug 24 13:40:02 UTC 2010 >Closed-Date: >Last-Modified: >Originator: Martin Beran >Release: FreeBSD 8.0-RELEASE-p2 i386 >Organization: Trusted Network Solutions, a. s. >Environment: System: FreeBSD mb.tns.cz 8.0-RELEASE-p2 FreeBSD 8.0-RELEASE-p2 #11: Thu Jul 29 16:49:38 CEST 2010 root@mb.tns.cz:/usr/obj/usr/src/sys/GENERIC i386 Observed also on FreeBSD 7.1. >Description: Function magic_buffer() from libmagic(3) uses external utilities for decompression of compressed files. Data from an input in-memory buffer should be passed to the external program via a pipe. Due to an incorrect condition, the pipe is not initialized, hence no data are passed to the program. Moreover, calling close(2) with an argument taken from an unitialized memory location causes closing of two indeterministically selected file descriptors. If the descriptor intended for reading from the decompression process is closed, the libmagic code will be stuck in an endless loop, using 100 % CPU, calling select(2) that always fails with EBADF. >How-To-Repeat: Call magic_buffer(m, buf, sz) for m obtained by a prior call of magic_open(MAGIC_COMPRESS), with buf containing data compressed by bzip2. >Fix: Apply the attached patch in /usr/src, recompile and reinstall /usr/src/lib/libmagic: diff -ru contrib.orig/file/compress.c contrib/file/compress.c --- contrib.orig/file/compress.c 2009-05-19 00:34:33.000000000 +0200 +++ contrib/file/compress.c 2010-08-24 15:09:11.000000000 +0200 @@ -197,6 +197,7 @@ if (selrv == -1) { if (errno == EINTR || errno == EAGAIN) continue; + return -1; } else if (selrv == 0 && cnt >= 5) { return 0; } else @@ -381,7 +382,7 @@ (void)fflush(stdout); (void)fflush(stderr); - if ((fd != -1 && pipe(fdin) == -1) || pipe(fdout) == -1) { + if ((fd == -1 && pipe(fdin) == -1) || pipe(fdout) == -1) { file_error(ms, errno, "cannot create pipe"); return NODATA; } >Release-Note: >Audit-Trail: >Unformatted:
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