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

[fangying <1840865@bugs.launchpad.net>]

** Description changed:

  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.
+ 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
+     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
+     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;
-         }
+     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) 
+       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*.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1840865

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

Status in QEMU:
  New

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*.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1840865/+subscriptions