diff options
| author | Stefan Weil <sw@weilnetz.de> | 2012-05-04 08:51:16 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2012-05-07 08:44:21 +0200 |
| commit | 68bd348ade453821fd5378479e6718e69bf181f1 (patch) | |
| tree | faa488a945cc55391e191d5e5cb80f6a6a9464d6 | |
| parent | 2a92fbff49a286ddad1686d60532d791f20f4ce1 (diff) | |
scsi: Add assertion for use-after-free errors
The QEMU emulation which is currently used with Raspberry PI images
(qemu-system-arm -M versatilepb ...) accesses memory which was freed.
Valgrind output (extract):
==17857== Invalid write of size 4
==17857== at 0x24EB06: scsi_req_unref (scsi-bus.c:1273)
==17857== by 0x24FFAE: scsi_read_complete (scsi-disk.c:277)
==17857== by 0x152ACC: bdrv_co_em_bh (block.c:3363)
==17857== by 0x13D49C: qemu_bh_poll (async.c:71)
==17857== by 0x211A8C: main_loop_wait (main-loop.c:503)
==17857== by 0x207954: main_loop (vl.c:1555)
==17857== by 0x20E9C9: main (vl.c:3653)
==17857== Address 0x1c54383c is 12 bytes inside a block of size 260 free'd
==17857== at 0x4824B3A: free (vg_replace_malloc.c:366)
==17857== by 0x20ADFA: free_and_trace (vl.c:2250)
==17857== by 0x4899FC5: g_free (in /lib/libglib-2.0.so.0.2400.1)
==17857== by 0x24EB3B: scsi_req_unref (scsi-bus.c:1277)
==17857== by 0x24F003: scsi_req_complete (scsi-bus.c:1383)
==17857== by 0x25022A: scsi_read_data (scsi-disk.c:334)
==17857== by 0x24EB9F: scsi_req_continue (scsi-bus.c:1289)
==17857== by 0x1C7787: lsi_do_dma (lsi53c895a.c:575)
==17857== by 0x1C8CDA: lsi_execute_script (lsi53c895a.c:1147)
==17857== by 0x1C74EA: lsi_resume_script (lsi53c895a.c:510)
==17857== by 0x1C7ECD: lsi_transfer_data (lsi53c895a.c:746)
==17857== by 0x24EC90: scsi_req_data (scsi-bus.c:1307)
(There are some more similar messages.)
This patch adds an assertion which also detects those errors:
Calling scsi_req_unref is not allowed when the previous call
of that function has decremented refcount to 0, because in this
case req was freed.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | hw/scsi-bus.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c index add1d4f28d..8ab9bcda86 100644 --- a/hw/scsi-bus.c +++ b/hw/scsi-bus.c @@ -1291,6 +1291,7 @@ SCSIRequest *scsi_req_ref(SCSIRequest *req) void scsi_req_unref(SCSIRequest *req) { + assert(req->refcount > 0); if (--req->refcount == 0) { if (req->ops->free_req) { req->ops->free_req(req); |