On Fri, May 17, 2019 at 5:36 PM Todd Kjos <tkjos@xxxxxxxxxx> wrote: > > From: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Date: Fri, May 17, 2019 at 3:26 AM > To: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos, Martijn Coenen, > Joel Fernandes, Christian Brauner, open list:ANDROID DRIVERS, LKML > Cc: syzkaller > > > Hi, > > > > I have 2 questions re drivers/android/binder.c stress testing. > > > > 1. Are there any docs on the kernel interface? Or some examples on how > > to use it and reference syscall sequences to make it do something > > meaningful? > > I hopefully figured out struct layouts and offsets of objects thing, > > but I still can't figure out handles, pointers, nodes, pointer to > > nodes... pointer to data (?), references, cookies and where does one > > get valid values for these. > > The kernel interface is not well documented since it isn't intended to > be used apart from libbinder. The best example for your purposes is > probably the binderDriverInterfaceTest which you can find at > https://android.googlesource.com/platform/frameworks/native/+/refs/heads/master/libs/binder/tests/binderDriverInterfaceTest.cpp. > > The libbinder source is at > https://android.googlesource.com/platform/frameworks/native/+/refs/heads/master/libs/binder. > > > > > 2. In my tests any transaction breaks binder device until the next reboot. > > If I open binder device twice, mmap, set context and then the process > > dies, then everything it released fine, in particular the context > > (context_mgr_node gone). So the device is ready for a next test: > > > > [ 40.247970][ T6239] binder: binder_open: 6238:6239 > > [ 40.250819][ T6239] binder: 6238:6239 node 1 u0000000000000000 > > c0000000000000000 created > > [ 40.253365][ T6239] binder: binder_mmap: 6238 200a0000-200a2000 (8 > > K) vma f9 pagep 8000000000000025 > > [ 40.256454][ T6239] binder: binder_open: 6238:6239 > > [ 40.259604][ T6239] binder: binder_mmap: 6238 200c0000-200c2000 (8 > > K) vma f9 pagep 8000000000000025 > > [ 40.271526][ T6238] binder: 6238 close vm area 200a0000-200a2000 (8 > > K) vma 180200d9 pagep 8000000000000025 > > [ 40.273113][ T6238] binder: 6238 close vm area 200c0000-200c2000 (8 > > K) vma 180200d9 pagep 8000000000000025 > > [ 40.275058][ T17] binder: binder_flush: 6238 woke 0 threads > > [ 40.275997][ T17] binder: binder_flush: 6238 woke 0 threads > > [ 40.276968][ T17] binder: binder_deferred_release: 6238 threads > > 0, nodes 0 (ref 0), refs 0, active transactions 0 > > [ 40.278626][ T17] binder: binder_deferred_release: 6238 > > context_mgr_node gone > > [ 40.279756][ T17] binder: binder_deferred_release: 6238 threads > > 1, nodes 1 (ref 0), refs 0, active transactions 0 > > > > > > However, if I also send a transaction between these fd's, then > > context_mgr_node is not released: > > > > [ 783.851403][ T6167] binder: binder_open: 6166:6167 > > [ 783.858801][ T6167] binder: 6166:6167 node 1 u0000000000000000 > > c0000000000000000 created > > [ 783.862458][ T6167] binder: binder_mmap: 6166 200a0000-200a2000 (8 > > K) vma f9 pagep 8000000000000025 > > [ 783.865777][ T6167] binder: binder_open: 6166:6167 > > [ 783.867892][ T6167] binder: binder_mmap: 6166 200c0000-200c2000 (8 > > K) vma f9 pagep 8000000000000025 > > [ 783.870810][ T6167] binder: 6166:6167 write 76 at 0000000020000180, > > read 0 at 0000000020000300 > > [ 783.872211][ T6167] binder: 6166:6167 BC_TRANSACTION 2 -> 6166 - > > node 1, data 0000000020000200-00000000200002c0 size 88-24-16 > > [ 783.873819][ T6167] binder: 6166:6167 node 3 u0000000000000000 > > c0000000000000000 created > > [ 783.875032][ T6167] binder: 6166 new ref 4 desc 1 for node 3 > > [ 783.875860][ T6167] binder: node 3 u0000000000000000 -> ref 4 desc 1 > > [ 783.876868][ T6167] binder: 6166:6167 wrote 76 of 76, read return 0 of 0 > > [ 783.886714][ T6167] binder: 6166 close vm area 200a0000-200a2000 (8 > > K) vma 180200d9 pagep 8000000000000025 > > [ 783.888161][ T6167] binder: 6166 close vm area 200c0000-200c2000 (8 > > K) vma 180200d9 pagep 8000000000000025 > > [ 783.890134][ T27] binder: binder_flush: 6166 woke 0 threads > > [ 783.891036][ T27] binder: binder_flush: 6166 woke 0 threads > > [ 783.892027][ T2903] binder: release 6166:6167 transaction 2 out, still active > > [ 783.893097][ T2903] binder: unexpected work type, 4, not freed > > [ 783.893947][ T2903] binder: undelivered TRANSACTION_COMPLETE > > [ 783.894849][ T2903] binder: node 3 now dead, refs 1, death 0 > > [ 783.895717][ T2903] binder: binder_deferred_release: 6166 threads > > 1, nodes 1 (ref 1), refs 0, active transactions 1 > > > > > > And all subsequent tests will fail because "BINDER_SET_CONTEXT_MGR > > already set" presumably to the now unrecoverably dead process: > > > > [ 831.085174][ T6191] binder: binder_open: 6190:6191 > > [ 831.087450][ T6191] binder: BINDER_SET_CONTEXT_MGR already set > > [ 831.088910][ T6191] binder: 6190:6191 ioctl 4018620d 200000c0 returned -16 > > [ 831.090626][ T6191] binder: binder_mmap: 6190 200a0000-200a2000 (8 > > K) vma f9 pagep 8000000000000025 > > [ 831.092783][ T6191] binder: binder_open: 6190:6191 > > [ 831.094076][ T6191] binder: binder_mmap: 6190 200c0000-200c2000 (8 > > K) vma f9 pagep 8000000000000025 > > [ 831.096218][ T6191] binder: 6190:6191 write 76 at 0000000020000180, > > read 0 at 0000000020000300 > > [ 831.097606][ T6191] binder: 6190:6191 BC_TRANSACTION 5 -> 6166 - > > node 1, data 0000000020000200-00000000200002c0 size 88-24-16 > > [ 831.099251][ T6191] binder_alloc: 6166: binder_alloc_buf, no vma > > [ 831.100433][ T6191] binder: 6190:6191 transaction failed 29189/-3, > > size 88-24 line 3157 > > [ 831.101559][ T6191] binder: 6190:6191 wrote 76 of 76, read return 0 of 0 > > [ 831.110317][ T6191] binder: 6190 close vm area 200a0000-200a2000 (8 > > K) vma 180200d9 pagep 8000000000000025 > > [ 831.111752][ T6191] binder: 6190 close vm area 200c0000-200c2000 (8 > > K) vma 180200d9 pagep 8000000000000025 > > [ 831.113266][ T3344] binder: binder_flush: 6190 woke 0 threads > > [ 831.114147][ T3344] binder: binder_flush: 6190 woke 0 threads > > [ 831.115087][ T3344] binder: undelivered TRANSACTION_ERROR: 29189 > > [ 831.115991][ T3344] binder: binder_deferred_release: 6190 threads > > 1, nodes 0 (ref 0), refs 0, active transactions 0 > > [ 831.117525][ T3344] binder: binder_deferred_release: 6190 threads > > 1, nodes 0 (ref 0), refs 0, active transactions 0 > > > > > > The question is: if processes that opened the device and ever mapped > > it are now completely gone, should it reset the original state when > > context can be bound again? Is it a bug in binder that it does not? If > > so, is there some kind of temp work-around for this? > > If all the processes that opened the device are gone, everything > should be cleaned up and leave binder in a useable state. When the > device is in this state, can you dump out > /sys/debug/kernel/binder/state and send it to me? Here it is: binder state: dead nodes: node 3: u0000000000000000 c0000000000000000 hs 0 hw 0 ls 0 lw 0 is 1 iw 1 tr 1 proc 6193 proc 6193 context binder0 thread 6194: l 00 need_return 1 tr 0 node 1: u0000000000000000 c0000000000000000 hs 1 hw 1 ls 2 lw 1 is 0 iw 0 tr 1 ref 4: desc 1 dead node 3 s 1 w 0 d 00000000e77aea3b buffer 2: 00000000b2301cfa size 88:24:16 active pending transaction 2: 00000000b1591166 from 0:0 to 6193:0 code 0 flags 0 pri 0 r1 node 1 size 88:24 data 00000000b2301cfa Kernel also said: [ 197.049702][ T12] binder: release 6193:6194 transaction 2 out, still active [ 197.050803][ T12] binder: unexpected work type, 4, not freed [ 197.051658][ T12] binder: undelivered TRANSACTION_COMPLETE Not sure why there is something unexpected. I don't try to fuzz it or something at this point. Just run a basic test. Here is the test, it's in syzkaller notation, but hopefully you can get overall idea: r0 = syz_open_dev$binder(&AUTO='/dev/binder#\x00', 0x0, 0x2) ioctl$BINDER_SET_CONTEXT_MGR_EXT(r0, AUTO, &AUTO={AUTO, 0x100, 0x0, 0x0}) mmap$binder(&(0x7f00000a0000), 0x2000, 0x1, 0x11, r0, 0x0) r1 = syz_open_dev$binder(&AUTO='/dev/binder#\x00', 0x0, 0x2) mmap$binder(&(0x7f00000c0000), 0x2000, 0x1, 0x11, r1, 0x0) ioctl$BINDER_WRITE_READ(r1, AUTO, &AUTO={AUTO, AUTO, &AUTO=[@transaction_sg={AUTO, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, AUTO, AUTO, &AUTO={@flat=@binder={AUTO, 0x0, 0x0, 0x0}, @fd={AUTO, AUTO, r0, AUTO, 0x0}, @ptr={AUTO, 0x0, &AUTO=""/10, AUTO, 0x0, 0x0}}, &AUTO={AUTO, AUTO, AUTO}}, 0x10}], AUTO, AUTO, &AUTO}) _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
