From 650d5c39753d095f8ae6cff418306cf1a6b8fd25 Mon Sep 17 00:00:00 2001

From: Jan Synacek <jsynacek@redhat.com>

Date: Fri, 2 Nov 2018 08:40:40 +0100

Subject: [PATCH] =?UTF-8?q?core:=20when=20deserializing=20state=20always?=

 =?UTF-8?q?=20use=20read=5Fline(=E2=80=A6,=20LONG=5FLINE=5FMAX,=20?=

 =?UTF-8?q?=E2=80=A6)?=

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This should be much better than fgets(), as we can read substantially

longer lines and overly long lines result in proper errors.

Fixes a vulnerability discovered by Jann Horn at Google.

(cherry picked from commit 8948b3415d762245ebf5e19d80b97d4d8cc208c1)

Resolves: CVE-2018-15686

[jsynacek] There were more commits in the pull request of which the cherry

picked commit was a part of, see

https://github.com/systemd/systemd/pull/10519/commits.

I decided not to backport any of the remaining ones, because they were

mostly irrelevant to the actual fix.

---

 src/core/job.c     | 19 +++++++++++--------

 src/core/manager.c | 38 ++++++++++++++++----------------------

 src/core/unit.c    | 17 ++++++++---------

 3 files changed, 35 insertions(+), 39 deletions(-)

diff --git a/src/core/job.c b/src/core/job.c

index 275503169b..998b231ed9 100644

--- a/src/core/job.c

+++ b/src/core/job.c

@@ -38,6 +38,7 @@

 #include "async.h"

 #include "virt.h"

 #include "dbus.h"

+#include "fileio.h"

 Job* job_new_raw(Unit *unit) {

         Job *j;

@@ -1035,23 +1036,25 @@ int job_serialize(Job *j, FILE *f, FDSet *fds) {

 }

 int job_deserialize(Job *j, FILE *f, FDSet *fds) {

+        int r = 0;

+

         assert(j);

         for (;;) {

-                char line[LINE_MAX], *l, *v;

+                _cleanup_free_ char *line = NULL;

+                char *l, *v;

                 size_t k;

-                if (!fgets(line, sizeof(line), f)) {

-                        if (feof(f))

-                                return 0;

-                        return -errno;

-                }

+                r = read_line(f, LONG_LINE_MAX, &line);

+                if (r < 0)

+                        return log_error_errno(r, "Failed to read serialization line: %m");

+                if (r == 0)

+                        return 0;

-                char_array_0(line);

                 l = strstrip(line);

                 /* End marker */

-                if (l[0] == 0)

+                if (isempty(l))

                         return 0;

                 k = strcspn(l, "=");

diff --git a/src/core/manager.c b/src/core/manager.c

index 0466e4bb8a..73d6c81fdb 100644

--- a/src/core/manager.c

+++ b/src/core/manager.c

@@ -37,6 +37,7 @@

 #include <sys/stat.h>

 #include <dirent.h>

 #include <sys/timerfd.h>

+#include <fileio.h>

 #ifdef HAVE_AUDIT

 #include <libaudit.h>

@@ -2559,21 +2560,19 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {

         m->n_reloading ++;

         for (;;) {

-                char line[LINE_MAX], *l;

+                _cleanup_free_ char *line = NULL;

+                char *l;

-                if (!fgets(line, sizeof(line), f)) {

-                        if (feof(f))

-                                r = 0;

-                        else

-                                r = -errno;

-                        goto finish;

-                }

+                r = read_line(f, LONG_LINE_MAX, &line);

+                if (r < 0)

+                        return log_error_errno(r, "Failed to read serialization line: %m");

+                if (r == 0)

+                        break;

-                char_array_0(line);

                 l = strstrip(line);

-                if (l[0] == 0)

+                 if (isempty(l)) /* end marker */

                         break;

                 if (startswith(l, "current-job-id=")) {

@@ -2708,22 +2707,17 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {

         }

         for (;;) {

+                _cleanup_free_ char *line = NULL;

                 Unit *u;

-                char name[UNIT_NAME_MAX+2];

                 /* Start marker */

-                if (!fgets(name, sizeof(name), f)) {

-                        if (feof(f))

-                                r = 0;

-                        else

-                                r = -errno;

-

-                        goto finish;

-                }

-

-                char_array_0(name);

+                r = read_line(f, LONG_LINE_MAX, &line);

+                if (r < 0)

+                        return log_error_errno(r, "Failed to read serialization line: %m");

+                if (r == 0)

+                        break;

-                r = manager_load_unit(m, strstrip(name), NULL, NULL, &u);

+                r = manager_load_unit(m, strstrip(line), NULL, NULL, &u);

                 if (r < 0)

                         goto finish;

diff --git a/src/core/unit.c b/src/core/unit.c

index e8532a057d..37fac8db3a 100644

--- a/src/core/unit.c

+++ b/src/core/unit.c

@@ -2644,20 +2644,19 @@ int unit_deserialize(Unit *u, FILE *f, FDSet *fds) {

                 rt = (ExecRuntime**) ((uint8_t*) u + offset);

         for (;;) {

-                char line[LINE_MAX], *l, *v;

+                 _cleanup_free_ char *line = NULL;

+                char *l, *v;

                 size_t k;

-                if (!fgets(line, sizeof(line), f)) {

-                        if (feof(f))

-                                return 0;

-                        return -errno;

-                }

+                r = read_line(f, LONG_LINE_MAX, &line);

+                if (r < 0)

+                        return log_error_errno(r, "Failed to read serialization line: %m");

+                if (r == 0) /* eof */

+                        return 0;

-                char_array_0(line);

                 l = strstrip(line);

-

                 /* End marker */

-                if (l[0] == 0)

+                if (isempty(l))

                         return 0;

                 k = strcspn(l, "=");