>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 [email protected]:/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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