On Mon, 12 Nov 2018 16:28:28 +0800 zhibin hu <noirf...@gmail.com> wrote:
> hi, > > i use this patch with qemu 3.0.0 and it seems not fix completely. > > [root@localhost ~]# ./qemu-system-x86_64 -snapshot -m 1024 -smp 2 > -enable-kvm -net nic,model=e1000 -net > tap,helper=/usr/libexec/qemu-bridge-helper -hda > /var/lib/libvirt/images/test.qcow2 -fsdev > local,id=test_dev,path=/tmp,security_model=none -device > virtio-9p-pci,fsdev=test_dev,mount_tag=test_mount -vnc 0.0.0.0:1 > ==5014==WARNING: ASan doesn't fully support makecontext/swapcontext > functions and may produce false positives in some cases! > ================================================================= > ==5014==ERROR: AddressSanitizer: heap-use-after-free on address > 0x60200014fc50 at pc 0x7f90c908697d bp 0x7f9053444970 sp 0x7f9053444118 > READ of size 2 at 0x60200014fc50 thread T17 > #0 0x7f90c908697c (/lib64/libasan.so.5+0x9997c) > #1 0x7f90c8452693 in g_path_get_basename > (/lib64/libglib-2.0.so.0+0x39693) > #2 0x559c1b78eb56 in local_lstat hw/9pfs/9p-local.c:182 > #3 0x559c1b799628 in v9fs_co_lstat hw/9pfs/cofile.c:53 > #4 0x559c1b777ee1 in fid_to_qid hw/9pfs/9p.c:598 > #5 0x559c1b77aeae in v9fs_attach hw/9pfs/9p.c:1017 > #6 0x559c1c145976 in coroutine_trampoline util/coroutine-ucontext.c:116 > #7 0x7f90bd6855ff in __correctly_grouped_prefixwc > (/lib64/libc.so.6+0x4c5ff) > > 0x60200014fc50 is located 0 bytes inside of 2-byte region > [0x60200014fc50,0x60200014fc52) > freed by thread T0 here: > #0 0x7f90c90db880 in __interceptor_free (/lib64/libasan.so.5+0xee880) > #1 0x7f90c846b4d1 in g_free (/lib64/libglib-2.0.so.0+0x524d1) > #2 0x559c1b775ce4 in v9fs_path_copy hw/9pfs/9p.c:195 > #3 0x559c1b78425d in v9fs_create hw/9pfs/9p.c:2297 Ah, so we have a similar issue when creating files with the older 9p2000 and 9p2000.u protocols... I'll try to come up with a fix. Cheers, -- Greg > #4 0x559c1c145976 in coroutine_trampoline util/coroutine-ucontext.c:116 > #5 0x7f90bd6855ff in __correctly_grouped_prefixwc > (/lib64/libc.so.6+0x4c5ff) > > previously allocated by thread T4 here: > #0 0x7f90c90dbc48 in malloc (/lib64/libasan.so.5+0xeec48) > #1 0x7f90bd743c37 in __GI___vasprintf_chk (/lib64/libc.so.6+0x10ac37) > > Thread T17 created by T16 here: > #0 0x7f90c9038443 in pthread_create (/lib64/libasan.so.5+0x4b443) > #1 0x559c1c10461e in qemu_thread_create util/qemu-thread-posix.c:534 > #2 0x559c1c0f2be4 in do_spawn_thread util/thread-pool.c:135 > #3 0x559c1c0f2498 in worker_thread util/thread-pool.c:83 > #4 0x559c1c1043e0 in qemu_thread_start util/qemu-thread-posix.c:504 > #5 0x7f90bd9ff593 in start_thread (/lib64/libpthread.so.0+0x7593) > > Thread T16 created by T0 here: > #0 0x7f90c9038443 in pthread_create (/lib64/libasan.so.5+0x4b443) > #1 0x559c1c10461e in qemu_thread_create util/qemu-thread-posix.c:534 > #2 0x559c1c0f2be4 in do_spawn_thread util/thread-pool.c:135 > #3 0x559c1c0f2c73 in spawn_thread_bh_fn util/thread-pool.c:143 > #4 0x559c1c0ef4d0 in aio_bh_call util/async.c:90 > #5 0x559c1c0ef787 in aio_bh_poll util/async.c:118 > #6 0x559c1c0fb5bd in aio_dispatch util/aio-posix.c:436 > #7 0x559c1c0f026f in aio_ctx_dispatch util/async.c:261 > #8 0x7f90c84658ac in g_main_context_dispatch > (/lib64/libglib-2.0.so.0+0x4c8ac) > > Thread T4 created by T0 here: > #0 0x7f90c9038443 in pthread_create (/lib64/libasan.so.5+0x4b443) > #1 0x559c1c10461e in qemu_thread_create util/qemu-thread-posix.c:534 > #2 0x559c1b2e7258 in qemu_kvm_start_vcpu /root/qemu-3.0.0/cpus.c:1935 > #3 0x559c1b2e7a0b in qemu_init_vcpu /root/qemu-3.0.0/cpus.c:2001 > #4 0x559c1b583f0c in x86_cpu_realizefn > /root/qemu-3.0.0/target/i386/cpu.c:4996 > #5 0x559c1b87f1e8 in device_set_realized hw/core/qdev.c:826 > #6 0x559c1bde6e62 in property_set_bool qom/object.c:1984 > #7 0x559c1bde2b0e in object_property_set qom/object.c:1176 > #8 0x559c1bde9b00 in object_property_set_qobject qom/qom-qobject.c:27 > #9 0x559c1bde2e2b in object_property_set_bool qom/object.c:1242 > #10 0x559c1b4f2452 in pc_new_cpu /root/qemu-3.0.0/hw/i386/pc.c:1107 > #11 0x559c1b4f2993 in pc_cpus_init /root/qemu-3.0.0/hw/i386/pc.c:1155 > #12 0x559c1b4fc9cb in pc_init1 /root/qemu-3.0.0/hw/i386/pc_piix.c:153 > #13 0x559c1b4fe81d in pc_init_v3_0 > /root/qemu-3.0.0/hw/i386/pc_piix.c:438 > #14 0x559c1b890f29 in machine_run_board_init hw/core/machine.c:830 > #15 0x559c1b6d246e in main /root/qemu-3.0.0/vl.c:4516 > #16 0x7f90bd65c11a in __libc_start_main (/lib64/libc.so.6+0x2311a) > > SUMMARY: AddressSanitizer: heap-use-after-free > (/lib64/libasan.so.5+0x9997c) > Shadow bytes around the buggy address: > 0x0c0480021f30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > 0x0c0480021f40: fa fa fd fa fa fa fd fd fa fa fa fa fa fa fa fa > 0x0c0480021f50: fa fa fa fa fa fa fa fa fa fa fd fa fa fa fd fd > 0x0c0480021f60: fa fa fd fa fa fa fa fa fa fa fd fa fa fa fa fa > 0x0c0480021f70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fd fa > =>0x0c0480021f80: fa fa fa fa fa fa fd fa fa fa[fd]fa fa fa fd fa > 0x0c0480021f90: fa fa fd fd fa fa fd fa fa fa fa fa fa fa fd fa > 0x0c0480021fa0: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fa fa > 0x0c0480021fb0: fa fa fd fa fa fa fa fa fa fa fa fa fa fa fd fd > 0x0c0480021fc0: fa fa fd fa fa fa fa fa fa fa fa fa fa fa fd fa > 0x0c0480021fd0: fa fa fd fa fa fa fd fa fa fa fa fa fa fa fd fa > 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 > ==5014==ABORTING > > thanks. > > On Wed, Nov 7, 2018 at 8:21 AM Greg Kurz <gr...@kaod.org> wrote: > > > The assumption that the fid cannot be used by any other operation is > > wrong. At least, nothing prevents a misbehaving client to create a > > file with a given fid, and to pass this fid to some other operation > > at the same time (ie, without waiting for the response to the creation > > request). The call to v9fs_path_copy() performed by the worker thread > > after the file was created can race with any access to the fid path > > performed by some other thread. This causes use-after-free issues that > > can be detected by ASAN with a custom 9p client. > > > > Unlike other operations that only read the fid path, v9fs_co_open2() > > does modify it. It should hence take the write lock. > > > > Cc: P J P <ppan...@redhat.com> > > Reported-by: zhibin hu <noirf...@gmail.com> > > Signed-off-by: Greg Kurz <gr...@kaod.org> > > --- > > hw/9pfs/cofile.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/hw/9pfs/cofile.c b/hw/9pfs/cofile.c > > index 88791bc327ac..9c22837cda32 100644 > > --- a/hw/9pfs/cofile.c > > +++ b/hw/9pfs/cofile.c > > @@ -140,10 +140,10 @@ int coroutine_fn v9fs_co_open2(V9fsPDU *pdu, > > V9fsFidState *fidp, > > cred.fc_gid = gid; > > /* > > * Hold the directory fid lock so that directory path name > > - * don't change. Read lock is fine because this fid cannot > > - * be used by any other operation. > > + * don't change. Take the write lock to be sure this fid > > + * cannot be used by another operation. > > */ > > - v9fs_path_read_lock(s); > > + v9fs_path_write_lock(s); > > v9fs_co_run_in_worker( > > { > > err = s->ops->open2(&s->ctx, &fidp->path, > > > >