With the reference in place in received_data(), the address sanitizer
now encounters a use-after-free when the destroy notification is
dispatched for the read watcher (see below).
Fix this by remove the destroy notification callback, as it isn't really
used except in the shutdown function.
==5797==ERROR: AddressSanitizer: heap-use-after-free on address 0x621000ac5904 at pc 0x55c1243b1f14 bp 0x7ffdef001340 sp 0x7ffdef001330
WRITE of size 4 at 0x621000ac5904 thread T0
#0 0x55c1243b1f13 in read_watcher_destroy_notify ../git/gatchat/gatmux.c:660
#1 0x7f08a8676742 (/usr/lib/libglib-2.0.so.0+0x62742)
#2 0x7f08a867e2e4 in g_main_context_dispatch (/usr/lib/libglib-2.0.so.0+0x6a2e4)
#3 0x7f08a8680210 (/usr/lib/libglib-2.0.so.0+0x6c210)
#4 0x7f08a8681122 in g_main_loop_run (/usr/lib/libglib-2.0.so.0+0x6d122)
#5 0x55c1243d6703 in main ../git/src/main.c:286
#6 0x7f08a8423152 in __libc_start_main (/usr/lib/libc.so.6+0x27152)
#7 0x55c1241fe1ad in _start (/home/martin/projects/ofono/x86/src/ofonod+0xfd1ad)
0x621000ac5904 is located 4 bytes inside of 4672-byte region [0x621000ac5900,0x621000ac6b40)
freed by thread T0 here:
#0 0x7f08a88cc6b0 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:122
#1 0x55c1243b1ebf in g_at_mux_unref ../git/gatchat/gatmux.c:652
#2 0x55c1243b062c in received_data ../git/gatchat/gatmux.c:276
#3 0x7f08a867e2ce in g_main_context_dispatch (/usr/lib/libglib-2.0.so.0+0x6a2ce)
previously allocated by thread T0 here:
#0 0x7f08a88cccd8 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:153
#1 0x55c1243b1bf1 in g_at_mux_new ../git/gatchat/gatmux.c:613
#2 0x55c1243b4b53 in g_at_mux_new_gsm0710_basic ../git/gatchat/gatmux.c:1172
#3 0x55c124386abd in cmux_gatmux ../git/plugins/quectel.c:871
#4 0x55c12438779f in cmux_cb ../git/plugins/quectel.c:1023
#5 0x55c1243a368e in at_chat_finish_command ../git/gatchat/gatchat.c:459
#6 0x55c1243a3bc8 in at_chat_handle_command_response ../git/gatchat/gatchat.c:521
#7 0x55c1243a4408 in have_line ../git/gatchat/gatchat.c:600
#8 0x55c1243a539e in new_bytes ../git/gatchat/gatchat.c:759
#9 0x55c1243ae2f9 in received_data ../git/gatchat/gatio.c:122
#10 0x7f08a867e2ce in g_main_context_dispatch (/usr/lib/libglib-2.0.so.0+0x6a2ce)
SUMMARY: AddressSanitizer: heap-use-after-free ../git/gatchat/gatmux.c:660 in read_watcher_destroy_notify
Shadow bytes around the buggy address:
0x0c4280150ad0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4280150ae0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4280150af0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4280150b00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4280150b10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c4280150b20:[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c4280150b30: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c4280150b40: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c4280150b50: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c4280150b60: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c4280150b70: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==5797==ABORTING
When closing down a cmux object, the address sanitizer detects a
use-after-free in gatmux.c (see below).
Avoid this by taking a reference to the mux object during the processing
in received_data().
ofonod[3640549]: ../git/plugins/quectel.c:cfun_disable() 0x610000000b40
ofonod[3640549]: ../git/plugins/quectel.c:close_serial() 0x610000000b40
ofonod[3640549]: ../git/plugins/quectel.c:close_mux() 0x610000000b40
ofonod[3640549]: ../git/examples/emulator.c:powered_watch() Removing modem 0x610000000b40 from the list
ofonod[3640549]: ../git/examples/emulator.c:powered_watch() Removing server watch: 106
ofonod[3640549]: ../git/src/modem.c:modem_change_state() old state: 0, new state: 0
=================================================================
==3640549==ERROR: AddressSanitizer: heap-use-after-free on address 0x62100073dd28 at pc 0x5566b6402a21 bp 0x7ffe7a2db0e0 sp 0x7ffe7a2db0d0
READ of size 8 at 0x62100073dd28 thread T0
#0 0x5566b6402a20 in debug ../git/gatchat/gatmux.c:109
#1 0x5566b6404bd7 in channel_close ../git/gatchat/gatmux.c:525
#2 0x7fa0516e44a6 in g_io_channel_shutdown (/usr/lib/libglib-2.0.so.0+0x774a6)
#3 0x7fa0516e4644 in g_io_channel_unref (/usr/lib/libglib-2.0.so.0+0x77644)
#4 0x5566b64048a4 in watch_finalize ../git/gatchat/gatmux.c:474
#5 0x7fa0516d6f6f (/usr/lib/libglib-2.0.so.0+0x69f6f)
#6 0x7fa0516ac6a7 in g_slist_foreach (/usr/lib/libglib-2.0.so.0+0x3f6a7)
#7 0x7fa0516b277b in g_slist_free_full (/usr/lib/libglib-2.0.so.0+0x4577b)
#8 0x5566b6403413 in dispatch_sources ../git/gatchat/gatmux.c:224
#9 0x5566b64039ea in received_data ../git/gatchat/gatmux.c:268
#10 0x7fa0516d727e in g_main_context_dispatch (/usr/lib/libglib-2.0.so.0+0x6a27e)
#11 0x7fa0516d91c0 (/usr/lib/libglib-2.0.so.0+0x6c1c0)
#12 0x7fa0516da0d2 in g_main_loop_run (/usr/lib/libglib-2.0.so.0+0x6d0d2)
#13 0x5566b6429b1b in main ../git/src/main.c:286
#14 0x7fa05147fee2 in __libc_start_main (/usr/lib/libc.so.6+0x26ee2)
#15 0x5566b62531ad in _start (/home/martin/projects/ofono/x86/src/ofonod+0xfc1ad)
0x62100073dd28 is located 40 bytes inside of 4672-byte region [0x62100073dd00,0x62100073ef40)
freed by thread T0 here:
#0 0x7fa0519256c0 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:122
#1 0x5566b64052d7 in g_at_mux_unref ../git/gatchat/gatmux.c:645
#2 0x5566b63d6d19 in close_mux ../git/plugins/quectel.c:199
#3 0x5566b63d7047 in close_serial ../git/plugins/quectel.c:223
#4 0x5566b63db62a in cfun_disable ../git/plugins/quectel.c:1056
#5 0x5566b63f6ae1 in at_chat_finish_command ../git/gatchat/gatchat.c:459
#6 0x5566b63f701b in at_chat_handle_command_response ../git/gatchat/gatchat.c:521
#7 0x5566b63f785b in have_line ../git/gatchat/gatchat.c:600
#8 0x5566b63f87f1 in new_bytes ../git/gatchat/gatchat.c:759
#9 0x5566b640174c in received_data ../git/gatchat/gatio.c:122
#10 0x5566b64047b4 in watch_dispatch ../git/gatchat/gatmux.c:464
#11 0x5566b640313b in dispatch_sources ../git/gatchat/gatmux.c:183
#12 0x5566b64039ea in received_data ../git/gatchat/gatmux.c:268
#13 0x7fa0516d727e in g_main_context_dispatch (/usr/lib/libglib-2.0.so.0+0x6a27e)
previously allocated by thread T0 here:
#0 0x7fa051925ce8 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:153
#1 0x5566b6405009 in g_at_mux_new ../git/gatchat/gatmux.c:606
#2 0x5566b6407f6b in g_at_mux_new_gsm0710_basic ../git/gatchat/gatmux.c:1165
#3 0x5566b63da9ba in cmux_cb ../git/plugins/quectel.c:882
#4 0x5566b63f6ae1 in at_chat_finish_command ../git/gatchat/gatchat.c:459
#5 0x5566b63f701b in at_chat_handle_command_response ../git/gatchat/gatchat.c:521
#6 0x5566b63f785b in have_line ../git/gatchat/gatchat.c:600
#7 0x5566b63f87f1 in new_bytes ../git/gatchat/gatchat.c:759
#8 0x5566b640174c in received_data ../git/gatchat/gatio.c:122
#9 0x7fa0516d727e in g_main_context_dispatch (/usr/lib/libglib-2.0.so.0+0x6a27e)
SUMMARY: AddressSanitizer: heap-use-after-free ../git/gatchat/gatmux.c:109 in debug
Shadow bytes around the buggy address:
0x0c42800dfb50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c42800dfb60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c42800dfb70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c42800dfb80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c42800dfb90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c42800dfba0: fd fd fd fd fd[fd]fd fd fd fd fd fd fd fd fd fd
0x0c42800dfbb0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c42800dfbc0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c42800dfbd0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c42800dfbe0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c42800dfbf0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==3640549==ABORTING
Otherwise write_watcher_destroy_notify can be invoked after
GAtMux has been deallocated which results in write after free:
==3952== Invalid write of size 4
==3952== at 0xABF54: write_watcher_destroy_notify (gatmux.c:285)
==3952== by 0x4AF21E7: g_source_callback_unref (gmain.c:1561)
==3952== by 0x4AF2E53: g_source_destroy_internal.constprop.8 (gmain.c:1207)
==3952== by 0x4AF61CF: g_main_dispatch (gmain.c:3177)
==3952== by 0x4AF61CF: g_main_context_dispatch (gmain.c:3769)
==3952== by 0x4AF658F: g_main_loop_run (gmain.c:4034)
==3952== by 0xBDDBB: main (main.c:261)
==3952== Address 0x50c6cb0 is 8 bytes inside a block of size 4,396 free'd
==3952== at 0x4840B28: free (vg_replace_malloc.c:530)
==3952== by 0xACB53: g_at_mux_unref (gatmux.c:642)
==3952== Block was alloc'd at
==3952== at 0x4841BF0: calloc (vg_replace_malloc.c:711)
==3952== by 0xAC9DF: g_at_mux_new (gatmux.c:603)
==3952== by 0xADF2F: g_at_mux_new_gsm0710_basic (gatmux.c:1160)
Leaving them there may result in invalid reads like this:
==2312== Invalid read of size 4
==2312== at 0xAB8C0: dispatch_sources (gatmux.c:134)
==2312== by 0xAC5D3: channel_close (gatmux.c:479)
==2312== by 0x4AE8885: g_io_channel_shutdown (giochannel.c:523)
==2312== by 0x4AE8A1D: g_io_channel_unref (giochannel.c:240)
==2312== by 0xAC423: watch_finalize (gatmux.c:426)
==2312== by 0x4AF2CC9: g_source_unref_internal (gmain.c:2048)
==2312== by 0x4AF44E1: g_source_destroy_internal (gmain.c:1230)
==2312== by 0x4AF44E1: g_source_destroy (gmain.c:1256)
==2312== by 0x4AF5257: g_source_remove (gmain.c:2282)
==2312== by 0xAB5CB: io_shutdown (gatio.c:325)
==2312== by 0xAB667: g_at_io_unref (gatio.c:345)
==2312== by 0xA72C7: at_chat_unref (gatchat.c:972)
==2312== by 0xA829B: g_at_chat_unref (gatchat.c:1446)
==2312== Address 0x51420f0 is 56 bytes inside a block of size 60 free'd
==2312== at 0x4840B28: free (vg_replace_malloc.c:530)
==2312== by 0x4AF2D33: g_source_unref_internal (gmain.c:2075)
==2312== by 0x4AF44E1: g_source_destroy_internal (gmain.c:1230)
==2312== by 0x4AF44E1: g_source_destroy (gmain.c:1256)
==2312== by 0x4AF5257: g_source_remove (gmain.c:2282)
==2312== by 0xAB46B: g_at_io_set_write_handler (gatio.c:283)
==2312== by 0xA713F: at_chat_suspend (gatchat.c:938)
==2312== by 0xA72B7: at_chat_unref (gatchat.c:971)
==2312== by 0xA829B: g_at_chat_unref (gatchat.c:1446)
==2312== Block was alloc'd at
==2312== at 0x4841BF0: calloc (vg_replace_malloc.c:711)
==2312== by 0x4AFB117: g_malloc0 (gmem.c:124)
==2312== by 0x4AF401F: g_source_new (gmain.c:892)
==2312== by 0xAC6A7: channel_create_watch (gatmux.c:506)
==2312== by 0x4AE7C4F: g_io_add_watch_full (giochannel.c:649)
==2312== by 0xAB4EB: g_at_io_set_write_handler (gatio.c:297)
==2312== by 0xA7103: chat_wakeup_writer (gatchat.c:931)
==2312== by 0xA753F: at_chat_send_common (gatchat.c:1045)
==2312== by 0xA850F: g_at_chat_send (gatchat.c:1502)
It's also necessary to add additional references to the sources
for the duration of the dispatch_sources loop because any source
can be removed when any callback is invoked (and not necessarily
the one being dispatched).
This patch was generated by the following semantic patch
(http://coccinelle.lip6.fr/)
// <smpl>
@fix disable is_null,isnt_null1@
expression *E;
@@
- !E
+ E == NULL
// </smpl>
GAtMux can now be made to work with multiple multiplexing protocols.
Currently on the 27.010 (07.10) Advanced and Basic modes are supported.
However, further protocol support can be added by providing the
necessary driver functions for GAtMux
Martin Hundebøll
Denis Kenzior
Marcel Holtmann
Slava Monich
Antoine Aubert
Lucas De Marchi