[Bug 1840865] Re: qemu crashes when doing iotest on virtio-9p filesystem

[Thomas Huth]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/181


** Changed in: qemu
       Status: New => Expired

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #181
   https://gitlab.com/qemu-project/qemu/-/issues/181

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https://bugs.launchpad.net/bugs/1840865

Title:
  qemu crashes when doing iotest on  virtio-9p filesystem

Status in QEMU:
  Expired

Bug description:
  Qemu crashes when doing avocado-vt test on virtio-9p filesystem.
  This bug can be reproduced running 
https://github.com/autotest/tp-qemu/blob/master/qemu/tests/9p.py with the 
latest qemu-4.0.0.
  The crash stack goes like:

  Program terminated with signal SIGSEGV, Segmentation fault.
  #0  v9fs_mark_fids_unreclaim (pdu=pdu@entry=0xaaab00046868, 
path=path@entry=0xffff851e2fa8)
      at hw/9pfs/9p.c:505
  #1  0x0000aaaae3585acc in v9fs_unlinkat (opaque=0xaaab00046868) at 
hw/9pfs/9p.c:2590
  #2  0x0000aaaae3811c10 in coroutine_trampoline (i0=<optimized out>, 
i1=<optimized out>)
      at util/coroutine-ucontext.c:116
  #3  0x0000ffffa13ddb20 in ?? () from /lib64/libc.so.6
  Backtrace stopped: not enough registers or memory available to unwind further

  A segment fault is triggered at hw/9pfs/9p.c line 505

      for (fidp = s->fid_list; fidp; fidp = fidp->next) {
          if (fidp->path.size != path->size) {     # fidp is invalid
              continue;
          }

  (gdb) p path
  $10 = (V9fsPath *) 0xffff851e2fa8
  (gdb) p *path
  $11 = {size = 21, data = 0xaaaafed6f420 "./9p_test/p2a1/d0/f1"}
  (gdb) p *fidp
  Cannot access memory at address 0x101010101010101
  (gdb) p *pdu
  $12 = {size = 19, tag = 54, id = 76 'L', cancelled = 0 '\000', complete = 
{entries = {
        sqh_first = 0x0, sqh_last = 0xaaab00046870}}, s = 0xaaab000454b8, next 
= {
      le_next = 0xaaab000467c0, le_prev = 0xaaab00046f88}, idx = 88}
  (gdb)

  Address Sanitizer shows error and saying that there is a heap-use-
  after-free on *fidp*.

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