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Resolves: #1976935 - tail: fix stack out-of-bounds write with --follow

This commit is contained in:
Kamil Dudka 2021-07-01 14:42:14 +02:00
parent 53174a96b5
commit eb70babab1
2 changed files with 189 additions and 4 deletions
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181
coreutils-8.32-tail-use-poll.patch Normal file
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@ -0,0 +1,181 @@
From c7a04cef4075da864a3468e63a5bb79334d8f556 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 26 Jun 2021 18:23:52 -0700
Subject: [PATCH] tail: use poll, not select
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
This fixes an unlikely stack out-of-bounds write reported by
Stepan Broz via Kamil Dudka (Bug#49209).
* src/tail.c: Do not include <sys/select.h>.
[!_AIX]: Include poll.h.
(check_output_alive) [!_AIX]: Use poll instead of select.
(tail_forever_inotify): Likewise. Simplify logic, as there is no
need for a ‘while (len <= evbuf_off)’ loop.
Upstream-commit: da0d448bca62c6305fc432f67e2c5ccc2da75346
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
src/tail.c | 100 +++++++++++++++++++++--------------------------------
1 file changed, 39 insertions(+), 61 deletions(-)
diff --git a/src/tail.c b/src/tail.c
index 1c88723..5b4f21a 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -28,12 +28,9 @@
#include <stdio.h>
#include <assert.h>
#include <getopt.h>
-#include <sys/select.h>
+#include <poll.h>
#include <sys/types.h>
#include <signal.h>
-#ifdef _AIX
-# include <poll.h>
-#endif
#include "system.h"
#include "argmatch.h"
@@ -351,27 +348,12 @@ check_output_alive (void)
if (! monitor_output)
return;
-#ifdef _AIX
- /* select on AIX was seen to give a readable event immediately. */
struct pollfd pfd;
pfd.fd = STDOUT_FILENO;
pfd.events = POLLERR;
if (poll (&pfd, 1, 0) >= 0 && (pfd.revents & POLLERR))
die_pipe ();
-#else
- struct timeval delay;
- delay.tv_sec = delay.tv_usec = 0;
-
- fd_set rfd;
- FD_ZERO (&rfd);
- FD_SET (STDOUT_FILENO, &rfd);
-
- /* readable event on STDOUT is equivalent to POLLERR,
- and implies an error condition on output like broken pipe. */
- if (select (STDOUT_FILENO + 1, &rfd, NULL, NULL, &delay) == 1)
- die_pipe ();
-#endif
}
static bool
@@ -1612,7 +1594,7 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,
/* Wait for inotify events and handle them. Events on directories
ensure that watched files can be re-added when following by name.
This loop blocks on the 'safe_read' call until a new event is notified.
- But when --pid=P is specified, tail usually waits via the select. */
+ But when --pid=P is specified, tail usually waits via poll. */
while (1)
{
struct File_spec *fspec;
@@ -1629,54 +1611,51 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files,
return false;
}
- /* When watching a PID, ensure that a read from WD will not block
- indefinitely. */
- while (len <= evbuf_off)
+ if (len <= evbuf_off)
{
- struct timeval delay; /* how long to wait for file changes. */
+ /* Poll for inotify events. When watching a PID, ensure
+ that a read from WD will not block indefinitely.
+ If MONITOR_OUTPUT, also poll for a broken output pipe. */
- if (pid)
+ int file_change;
+ struct pollfd pfd[2];
+ do
{
- if (writer_is_dead)
- exit (EXIT_SUCCESS);
+ /* How many ms to wait for changes. -1 means wait forever. */
+ int delay = -1;
- writer_is_dead = (kill (pid, 0) != 0 && errno != EPERM);
-
- if (writer_is_dead)
- delay.tv_sec = delay.tv_usec = 0;
- else
+ if (pid)
{
- delay.tv_sec = (time_t) sleep_interval;
- delay.tv_usec = 1000000 * (sleep_interval - delay.tv_sec);
+ if (writer_is_dead)
+ exit (EXIT_SUCCESS);
+
+ writer_is_dead = (kill (pid, 0) != 0 && errno != EPERM);
+
+ if (writer_is_dead || sleep_interval <= 0)
+ delay = 0;
+ else if (sleep_interval < INT_MAX / 1000 - 1)
+ {
+ /* delay = ceil (sleep_interval * 1000), sans libm. */
+ double ddelay = sleep_interval * 1000;
+ delay = ddelay;
+ delay += delay < ddelay;
+ }
}
+
+ pfd[0].fd = wd;
+ pfd[0].events = POLLIN;
+ pfd[1].fd = STDOUT_FILENO;
+ pfd[1].events = pfd[1].revents = 0;
+ file_change = poll (pfd, monitor_output + 1, delay);
}
+ while (file_change == 0);
- fd_set rfd;
- FD_ZERO (&rfd);
- FD_SET (wd, &rfd);
- if (monitor_output)
- FD_SET (STDOUT_FILENO, &rfd);
-
- int file_change = select (MAX (wd, STDOUT_FILENO) + 1,
- &rfd, NULL, NULL, pid ? &delay: NULL);
-
- if (file_change == 0)
- continue;
- else if (file_change == -1)
- die (EXIT_FAILURE, errno,
- _("error waiting for inotify and output events"));
- else if (FD_ISSET (STDOUT_FILENO, &rfd))
- {
- /* readable event on STDOUT is equivalent to POLLERR,
- and implies an error on output like broken pipe. */
- die_pipe ();
- }
- else
- break;
- }
+ if (file_change < 0)
+ die (EXIT_FAILURE, errno,
+ _("error waiting for inotify and output events"));
+ if (pfd[1].revents)
+ die_pipe ();
- if (len <= evbuf_off)
- {
len = safe_read (wd, evbuf, evlen);
evbuf_off = 0;
@@ -2437,8 +2416,7 @@ main (int argc, char **argv)
if (forever && ignore_fifo_and_pipe (F, n_files))
{
/* If stdout is a fifo or pipe, then monitor it
- so that we exit if the reader goes away.
- Note select() on a regular file is always readable. */
+ so that we exit if the reader goes away. */
struct stat out_stat;
if (fstat (STDOUT_FILENO, &out_stat) < 0)
die (EXIT_FAILURE, errno, _("standard output"));
--
2.31.1

12
coreutils.spec
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@ -1,7 +1,7 @@
Summary: A set of basic GNU tools commonly used in shell scripts
Name: coreutils
Version: 8.32
Release: 28%{?dist}
Release: 29%{?dist}
License: GPLv3+
Url: https://www.gnu.org/software/coreutils/
Source0: https://ftp.gnu.org/gnu/%{name}/%{name}-%{version}.tar.xz
@ -58,6 +58,9 @@ Patch14: coreutils-8.32-tests-false-positives.patch
# mountlist: recognize fuse.portal as dummy file system (#1913358)
Patch15: coreutils-8.32-fuse-portal.patch
# tail: fix stack out-of-bounds write with --follow
Patch16: coreutils-8.32-tail-use-poll.patch
# disable the test-lock gnulib test prone to deadlock
Patch100: coreutils-8.26-test-lock.patch
@ -314,10 +317,11 @@ rm -f $RPM_BUILD_ROOT%{_infodir}/dir
%license COPYING
%changelog
* Tue Jun 15 2021 Mohan Boddu <mboddu@redhat.com>
- Rebuilt for RHEL 9 BETA for openssl 3.0
* Thu Jul 01 2021 Kamil Dudka <kdudka@redhat.com> - 8.32-29
- tail: fix stack out-of-bounds write with --follow (#1976935)
Related: rhbz#1971065
* Tue Jun 15 2021 Mohan Boddu <mboddu@redhat.com> - 8.32-28
- Rebuilt for RHEL 9 BETA for openssl 3.0 (#1971065)
* Tue Jun 08 2021 Kamil Dudka <kdudka@redhat.com> - 8.32-27
- mountlist: recognize fuse.portal as dummy file system (#1913358)