From a4ead9514b411945f9525ac33901db2b557ce9d0 Mon Sep 17 00:00:00 2001

From: Evgeny Vereshchagin <evvers@ya.ru>

Date: Mon, 9 Jan 2017 04:46:11 +0000

Subject: [PATCH] shared: fix double free in link

Fixes:

```

touch hola.service

systemctl link $(pwd)/hola.service $(pwd)/hola.service

```

```

==1==ERROR: AddressSanitizer: attempting double-free on 0x60300002c560 in thread T0 (systemd):

    #0 0x7fc8c961cb00 in free (/lib64/libasan.so.3+0xc6b00)

    #1 0x7fc8c90ebd3b in strv_clear src/basic/strv.c:83

    #2 0x7fc8c90ebdb6 in strv_free src/basic/strv.c:89

    #3 0x55637c758c77 in strv_freep src/basic/strv.h:37

    #4 0x55637c763ba9 in method_enable_unit_files_generic src/core/dbus-manager.c:1960

    #5 0x55637c763d16 in method_link_unit_files src/core/dbus-manager.c:2001

    #6 0x7fc8c92537ec in method_callbacks_run src/libsystemd/sd-bus/bus-objects.c:418

    #7 0x7fc8c9258830 in object_find_and_run src/libsystemd/sd-bus/bus-objects.c:1255

    #8 0x7fc8c92594d7 in bus_process_object src/libsystemd/sd-bus/bus-objects.c:1371

    #9 0x7fc8c91e7553 in process_message src/libsystemd/sd-bus/sd-bus.c:2563

    #10 0x7fc8c91e78ce in process_running src/libsystemd/sd-bus/sd-bus.c:2605

    #11 0x7fc8c91e8f61 in bus_process_internal src/libsystemd/sd-bus/sd-bus.c:2837

    #12 0x7fc8c91e90d2 in sd_bus_process src/libsystemd/sd-bus/sd-bus.c:2856

    #13 0x7fc8c91ea8f9 in io_callback src/libsystemd/sd-bus/sd-bus.c:3126

    #14 0x7fc8c928333b in source_dispatch src/libsystemd/sd-event/sd-event.c:2268

    #15 0x7fc8c9285cf7 in sd_event_dispatch src/libsystemd/sd-event/sd-event.c:2627

    #16 0x7fc8c92865fa in sd_event_run src/libsystemd/sd-event/sd-event.c:2686

    #17 0x55637c6b5257 in manager_loop src/core/manager.c:2274

    #18 0x55637c6a2194 in main src/core/main.c:1920

    #19 0x7fc8c7ac7400 in __libc_start_main (/lib64/libc.so.6+0x20400)

    #20 0x55637c697339 in _start (/usr/lib/systemd/systemd+0xcd339)

0x60300002c560 is located 0 bytes inside of 19-byte region [0x60300002c560,0x60300002c573)

freed by thread T0 (systemd) here:

    #0 0x7fc8c961cb00 in free (/lib64/libasan.so.3+0xc6b00)

    #1 0x7fc8c90ee320 in strv_remove src/basic/strv.c:630

    #2 0x7fc8c90ee190 in strv_uniq src/basic/strv.c:602

    #3 0x7fc8c9180533 in unit_file_link src/shared/install.c:1996

    #4 0x55637c763b25 in method_enable_unit_files_generic src/core/dbus-manager.c:1985

    #5 0x55637c763d16 in method_link_unit_files src/core/dbus-manager.c:2001

    #6 0x7fc8c92537ec in method_callbacks_run src/libsystemd/sd-bus/bus-objects.c:418

    #7 0x7fc8c9258830 in object_find_and_run src/libsystemd/sd-bus/bus-objects.c:1255

    #8 0x7fc8c92594d7 in bus_process_object src/libsystemd/sd-bus/bus-objects.c:1371

    #9 0x7fc8c91e7553 in process_message src/libsystemd/sd-bus/sd-bus.c:2563

    #10 0x7fc8c91e78ce in process_running src/libsystemd/sd-bus/sd-bus.c:2605

    #11 0x7fc8c91e8f61 in bus_process_internal src/libsystemd/sd-bus/sd-bus.c:2837

    #12 0x7fc8c91e90d2 in sd_bus_process src/libsystemd/sd-bus/sd-bus.c:2856

    #13 0x7fc8c91ea8f9 in io_callback src/libsystemd/sd-bus/sd-bus.c:3126

    #14 0x7fc8c928333b in source_dispatch src/libsystemd/sd-event/sd-event.c:2268

    #15 0x7fc8c9285cf7 in sd_event_dispatch src/libsystemd/sd-event/sd-event.c:2627

    #16 0x7fc8c92865fa in sd_event_run src/libsystemd/sd-event/sd-event.c:2686

    #17 0x55637c6b5257 in manager_loop src/core/manager.c:2274

    #18 0x55637c6a2194 in main src/core/main.c:1920

        #19 0x7fc8c7ac7400 in __libc_start_main (/lib64/libc.so.6+0x20400)

previously allocated by thread T0 (systemd) here:

    #0 0x7fc8c95b0160 in strdup (/lib64/libasan.so.3+0x5a160)

    #1 0x7fc8c90edf32 in strv_extend src/basic/strv.c:552

    #2 0x7fc8c923ae41 in bus_message_read_strv_extend src/libsystemd/sd-bus/bus-message.c:5578

    #3 0x7fc8c923b0de in sd_bus_message_read_strv src/libsystemd/sd-bus/bus-message.c:5600

    #4 0x55637c7639d1 in method_enable_unit_files_generic src/core/dbus-manager.c:1969

    #5 0x55637c763d16 in method_link_unit_files src/core/dbus-manager.c:2001

    #6 0x7fc8c92537ec in method_callbacks_run src/libsystemd/sd-bus/bus-objects.c:418

    #7 0x7fc8c9258830 in object_find_and_run src/libsystemd/sd-bus/bus-objects.c:1255

    #8 0x7fc8c92594d7 in bus_process_object src/libsystemd/sd-bus/bus-objects.c:1371

    #9 0x7fc8c91e7553 in process_message src/libsystemd/sd-bus/sd-bus.c:2563

    #10 0x7fc8c91e78ce in process_running src/libsystemd/sd-bus/sd-bus.c:2605

    #11 0x7fc8c91e8f61 in bus_process_internal src/libsystemd/sd-bus/sd-bus.c:2837

    #12 0x7fc8c91e90d2 in sd_bus_process src/libsystemd/sd-bus/sd-bus.c:2856

    #13 0x7fc8c91ea8f9 in io_callback src/libsystemd/sd-bus/sd-bus.c:3126

    #14 0x7fc8c928333b in source_dispatch src/libsystemd/sd-event/sd-event.c:2268

    #15 0x7fc8c9285cf7 in sd_event_dispatch src/libsystemd/sd-event/sd-event.c:2627

    #16 0x7fc8c92865fa in sd_event_run src/libsystemd/sd-event/sd-event.c:2686

    #17 0x55637c6b5257 in manager_loop src/core/manager.c:2274

    #18 0x55637c6a2194 in main src/core/main.c:1920

    #19 0x7fc8c7ac7400 in __libc_start_main (/lib64/libc.so.6+0x20400)

SUMMARY: AddressSanitizer: double-free (/lib64/libasan.so.3+0xc6b00) in free

==1==ABORTING

```

Closes #5015

(cherry picked from commit 8af35ba681116eb79a46e3dbd65b166c1efd6164)

---

 src/shared/install.c | 8 ++++++--

 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/shared/install.c b/src/shared/install.c

index 5f0eec3ccb..64fe522ebb 100644

--- a/src/shared/install.c

+++ b/src/shared/install.c

@@ -1947,7 +1947,7 @@ int unit_file_link(

                 unsigned *n_changes) {

         _cleanup_lookup_paths_free_ LookupPaths paths = {};

-        _cleanup_free_ char **todo = NULL;

+        _cleanup_strv_free_ char **todo = NULL;

         size_t n_todo = 0, n_allocated = 0;

         const char *config_path;

         char **i;

@@ -1996,7 +1996,11 @@ int unit_file_link(

                 if (!GREEDY_REALLOC0(todo, n_allocated, n_todo + 2))

                         return -ENOMEM;

-                todo[n_todo++] = *i;

+                todo[n_todo] = strdup(*i);

+                if (!todo[n_todo])

+                        return -ENOMEM;

+

+                n_todo++;

         }

         strv_uniq(todo);