file: fix close_on_exec for multithreaded decompression

It is not safe to call the 'file' command from multiple threads. When a
file is checked with multiple threads in parallel, the file descriptors
might get shared which makes the pipe handling lock up, leading to lock
up in rpmbuild. And may lead to rarely deadlock on random recipes's
do_package task.

Signed-off-by: Changqing Li <changqing.li@windriver.com>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>

2 files changed, 222 insertions, 1 deletions

diff --git a/meta/recipes-devtools/file/file_5.39.bb b/meta/recipes-devtools/file/file_5.39.bb
index abaa8149a3..c0c7253688 100644
--- a/meta/recipes-devtools/file/file_5.39.bb
+++ b/meta/recipes-devtools/file/file_5.39.bb
@@ -12,7 +12,8 @@ DEPENDS = "file-replacement-native"
 DEPENDS_class-native = "bzip2-replacement-native"
 
 SRC_URI = "git://github.com/file/file.git \
-           file://0001-src-compress.c-correct-header-define-for-xz-lzma.patch"
+           file://0001-src-compress.c-correct-header-define-for-xz-lzma.patch \
+           file://0001-Fix-close_on_exec-multithreaded-decompression-issue.patch"
 
 SRCREV = "87731415de945660b00f02207d8e9d986ef9b82e"
 S = "${WORKDIR}/git"
diff --git a/meta/recipes-devtools/file/files/0001-Fix-close_on_exec-multithreaded-decompression-issue.patch b/meta/recipes-devtools/file/files/0001-Fix-close_on_exec-multithreaded-decompression-issue.patch
new file mode 100644
index 0000000000..42105feed9
--- /dev/null
+++ b/meta/recipes-devtools/file/files/0001-Fix-close_on_exec-multithreaded-decompression-issue.patch
@@ -0,0 +1,220 @@
+From 0d82f2f3ba4a856504f23a9db1dd5f37bd076337 Mon Sep 17 00:00:00 2001
+From: Changqing Li <changqing.li@windriver.com>
+Date: Mon, 23 Aug 2021 14:16:53 +0800
+Subject: [PATCH] Fix close_on_exec multithreaded decompression issue.
+
+Upstream-Status: Backport [https://github.com/file/file/commit/81f15c2b0d6e9eaf524ff7bab37426c21af75fb7]
+Signed-off-by: Changqing Li <changqing.li@windriver.com>
+---
+ ChangeLog      |  5 +++++
+ configure.ac   |  2 +-
+ src/compress.c | 25 ++++++++++++++++++++++---
+ src/file.h     | 12 +++++++++++-
+ src/funcs.c    | 24 +++++++++++++++++++++++-
+ src/magic.c    |  7 +++++--
+ 6 files changed, 67 insertions(+), 8 deletions(-)
+
+diff --git a/ChangeLog b/ChangeLog
+index f877ad22..8c4a43d4 100644
+--- a/ChangeLog
++++ b/ChangeLog
+@@ -1,3 +1,8 @@
++2020-12-08  16:24  Christos Zoulas <christos@zoulas.com>
++
++	* fix multithreaded decompression file descriptor issue
++	  by using close-on-exec (Denys Vlasenko)
++
+ 2020-06-14  20:02  Christos Zoulas <christos@zoulas.com>
+ 
+ 	* release 5.39
+diff --git a/configure.ac b/configure.ac
+index 64c9f42e..521dc12d 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -166,7 +166,7 @@ else
+ fi])
+ 
+ dnl Checks for functions
+-AC_CHECK_FUNCS(strndup mkstemp mkostemp utimes utime wcwidth strtof newlocale uselocale freelocale memmem)
++AC_CHECK_FUNCS(strndup mkstemp mkostemp utimes utime wcwidth strtof newlocale uselocale freelocale memmem pipe2)
+ 
+ dnl Provide implementation of some required functions if necessary
+ AC_REPLACE_FUNCS(getopt_long asprintf vasprintf strlcpy strlcat getline ctime_r asctime_r localtime_r gmtime_r pread strcasestr fmtcheck dprintf)
+diff --git a/src/compress.c b/src/compress.c
+index 9670b72c..9f65e4fa 100644
+--- a/src/compress.c
++++ b/src/compress.c
+@@ -35,7 +35,7 @@
+ #include "file.h"
+ 
+ #ifndef lint
+-FILE_RCSID("@(#)$File: compress.c,v 1.127 2020/05/31 00:11:06 christos Exp $")
++FILE_RCSID("@(#)$File: compress.c,v 1.129 2020/12/08 21:26:00 christos Exp $")
+ #endif
+ 
+ #include "magic.h"
+@@ -844,8 +844,23 @@ uncompressbuf(int fd, size_t bytes_max, size_t method, const unsigned char *old,
+ 	for (i = 0; i < __arraycount(fdp); i++)
+ 		fdp[i][0] = fdp[i][1] = -1;
+ 
+-	if ((fd == -1 && pipe(fdp[STDIN_FILENO]) == -1) ||
+-	    pipe(fdp[STDOUT_FILENO]) == -1 || pipe(fdp[STDERR_FILENO]) == -1) {
++	/*
++	 * There are multithreaded users who run magic_file()
++	 * from dozens of threads. If two parallel magic_file() calls
++	 * analyze two large compressed files, both will spawn
++	 * an uncompressing child here, which writes out uncompressed data.
++	 * We read some portion, then close the pipe, then waitpid() the child.
++	 * If uncompressed data is larger, child shound get EPIPE and exit.
++	 * However, with *parallel* calls OTHER child may unintentionally
++	 * inherit pipe fds, thus keeping pipe open and making writes in
++	 * our child block instead of failing with EPIPE!
++	 * (For the bug to occur, two threads must mutually inherit their pipes,
++	 * and both must have large outputs. Thus it happens not that often).
++	 * To avoid this, be sure to create pipes with O_CLOEXEC.
++	 */
++	if ((fd == -1 && file_pipe_closexec(fdp[STDIN_FILENO]) == -1) ||
++	    file_pipe_closexec(fdp[STDOUT_FILENO]) == -1 ||
++	    file_pipe_closexec(fdp[STDERR_FILENO]) == -1) {
+ 		closep(fdp[STDIN_FILENO]);
+ 		closep(fdp[STDOUT_FILENO]);
+ 		return makeerror(newch, n, "Cannot create pipe, %s",
+@@ -876,16 +891,20 @@ uncompressbuf(int fd, size_t bytes_max, size_t method, const unsigned char *old,
+ 			if (fdp[STDIN_FILENO][1] > 2)
+ 				(void) close(fdp[STDIN_FILENO][1]);
+ 		}
++		file_clear_closexec(STDIN_FILENO);
++
+ ///FIXME: if one of the fdp[i][j] is 0 or 1, this can bomb spectacularly
+ 		if (copydesc(STDOUT_FILENO, fdp[STDOUT_FILENO][1]))
+ 			(void) close(fdp[STDOUT_FILENO][1]);
+ 		if (fdp[STDOUT_FILENO][0] > 2)
+ 			(void) close(fdp[STDOUT_FILENO][0]);
++		file_clear_closexec(STDOUT_FILENO);
+ 
+ 		if (copydesc(STDERR_FILENO, fdp[STDERR_FILENO][1]))
+ 			(void) close(fdp[STDERR_FILENO][1]);
+ 		if (fdp[STDERR_FILENO][0] > 2)
+ 			(void) close(fdp[STDERR_FILENO][0]);
++		file_clear_closexec(STDERR_FILENO);
+ 
+ 		(void)execvp(compr[method].argv[0],
+ 		    RCAST(char *const *, RCAST(intptr_t, compr[method].argv)));
+diff --git a/src/file.h b/src/file.h
+index 28ebc0c1..48f4b698 100644
+--- a/src/file.h
++++ b/src/file.h
+@@ -27,7 +27,7 @@
+  */
+ /*
+  * file.h - definitions for file(1) program
+- * @(#)$File: file.h,v 1.220 2020/06/08 17:38:27 christos Exp $
++ * @(#)$File: file.h,v 1.223 2020/12/08 21:26:00 christos Exp $
+  */
+ 
+ #ifndef __file_h__
+@@ -143,6 +143,14 @@
+ #define	MAX(a,b)	(((a) > (b)) ? (a) : (b))
+ #endif
+ 
++#ifndef O_CLOEXEC
++# define O_CLOEXEC 0
++#endif
++
++#ifndef FD_CLOEXEC
++# define FD_CLOEXEC 1
++#endif
++
+ #define FILE_BADSIZE CAST(size_t, ~0ul)
+ #define MAXDESC	64		/* max len of text description/MIME type */
+ #define MAXMIME	80		/* max len of text MIME type */
+@@ -538,6 +546,8 @@ protected char * file_printable(char *, size_t, const char *, size_t);
+ protected int file_os2_apptype(struct magic_set *, const char *, const void *,
+     size_t);
+ #endif /* __EMX__ */
++protected int file_pipe_closexec(int *);
++protected int file_clear_closexec(int);
+ 
+ protected void buffer_init(struct buffer *, int, const struct stat *,
+     const void *, size_t);
+diff --git a/src/funcs.c b/src/funcs.c
+index b66510c6..d6c485fe 100644
+--- a/src/funcs.c
++++ b/src/funcs.c
+@@ -27,7 +27,7 @@
+ #include "file.h"
+ 
+ #ifndef	lint
+-FILE_RCSID("@(#)$File: funcs.c,v 1.115 2020/02/20 15:50:20 christos Exp $")
++FILE_RCSID("@(#)$File: funcs.c,v 1.118 2020/12/08 21:26:00 christos Exp $")
+ #endif	/* lint */
+ 
+ #include "magic.h"
+@@ -36,6 +36,9 @@ FILE_RCSID("@(#)$File: funcs.c,v 1.115 2020/02/20 15:50:20 christos Exp $")
+ #include <stdlib.h>
+ #include <string.h>
+ #include <ctype.h>
++#ifdef HAVE_UNISTD_H
++#include <unistd.h>	/* for pipe2() */
++#endif
+ #if defined(HAVE_WCHAR_H)
+ #include <wchar.h>
+ #endif
+@@ -783,3 +786,22 @@ file_print_guid(char *str, size_t len, const uint64_t *guid)
+ 	    g->data4[2], g->data4[3], g->data4[4], g->data4[5],
+ 	    g->data4[6], g->data4[7]);
+ }
++
++protected int
++file_pipe_closexec(int *fds)
++{
++#ifdef HAVE_PIPE2
++	return pipe2(fds, O_CLOEXEC);
++#else
++	if (pipe(fds) == -1)
++		return -1;
++	(void)fcntl(fds[0], F_SETFD, FD_CLOEXEC);
++	(void)fcntl(fds[1], F_SETFD, FD_CLOEXEC);
++	return 0;
++#endif
++}
++
++protected int
++file_clear_closexec(int fd) {
++	return fcntl(fd, F_SETFD, 0);
++}
+diff --git a/src/magic.c b/src/magic.c
+index 17a7077d..89f4e16c 100644
+--- a/src/magic.c
++++ b/src/magic.c
+@@ -33,7 +33,7 @@
+ #include "file.h"
+ 
+ #ifndef	lint
+-FILE_RCSID("@(#)$File: magic.c,v 1.112 2020/06/08 19:44:10 christos Exp $")
++FILE_RCSID("@(#)$File: magic.c,v 1.113 2020/12/08 21:26:00 christos Exp $")
+ #endif	/* lint */
+ 
+ #include "magic.h"
+@@ -436,7 +436,7 @@ file_or_fd(struct magic_set *ms, const char *inname, int fd)
+ 		_setmode(STDIN_FILENO, O_BINARY);
+ #endif
+ 	if (inname != NULL) {
+-		int flags = O_RDONLY|O_BINARY|O_NONBLOCK;
++		int flags = O_RDONLY|O_BINARY|O_NONBLOCK|O_CLOEXEC;
+ 		errno = 0;
+ 		if ((fd = open(inname, flags)) < 0) {
+ 			okstat = stat(inname, &sb) == 0;
+@@ -460,6 +460,9 @@ file_or_fd(struct magic_set *ms, const char *inname, int fd)
+ 			rv = 0;
+ 			goto done;
+ 		}
++#if O_CLOEXEC == 0
++		(void)fcntl(fd, F_SETFD, FD_CLOEXEC);
++#endif
+ 	}
+ 
+ 	if (fd != -1) {
+-- 
+2.17.1
+