megasas: fix sglist leak

tests/cdrom-test -p /x86_64/cdrom/boot/megasas

Produces the following ASAN leak.

==25700==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x7f06f8faac48 in malloc (/lib64/libasan.so.5+0xeec48)
    #1 0x7f06f87a73c5 in g_malloc (/lib64/libglib-2.0.so.0+0x523c5)
    #2 0x55a729f17738 in pci_dma_sglist_init /home/elmarco/src/qq/include/hw/pci/pci.h:818
    #3 0x55a729f2a706 in megasas_map_dcmd /home/elmarco/src/qq/hw/scsi/megasas.c:698
    #4 0x55a729f39421 in megasas_handle_dcmd /home/elmarco/src/qq/hw/scsi/megasas.c:1574
    #5 0x55a729f3f70d in megasas_handle_frame /home/elmarco/src/qq/hw/scsi/megasas.c:1955
    #6 0x55a729f40939 in megasas_mmio_write /home/elmarco/src/qq/hw/scsi/megasas.c:2119
    #7 0x55a729f41102 in megasas_port_write /home/elmarco/src/qq/hw/scsi/megasas.c:2170
    #8 0x55a729220e60 in memory_region_write_accessor /home/elmarco/src/qq/memory.c:527
    #9 0x55a7292212b3 in access_with_adjusted_size /home/elmarco/src/qq/memory.c:594
    #10 0x55a72922cf70 in memory_region_dispatch_write /home/elmarco/src/qq/memory.c:1473
    #11 0x55a7290f5907 in flatview_write_continue /home/elmarco/src/qq/exec.c:3255
    #12 0x55a7290f5ceb in flatview_write /home/elmarco/src/qq/exec.c:3294
    #13 0x55a7290f6457 in address_space_write /home/elmarco/src/qq/exec.c:3384
    #14 0x55a7290f64a8 in address_space_rw /home/elmarco/src/qq/exec.c:3395
    #15 0x55a72929ecb0 in kvm_handle_io /home/elmarco/src/qq/accel/kvm/kvm-all.c:1729
    #16 0x55a7292a0db5 in kvm_cpu_exec /home/elmarco/src/qq/accel/kvm/kvm-all.c:1969
    #17 0x55a7291c4212 in qemu_kvm_cpu_thread_fn /home/elmarco/src/qq/cpus.c:1215
    #18 0x55a72a966a6c in qemu_thread_start /home/elmarco/src/qq/util/qemu-thread-posix.c:504
    #19 0x7f06ed486593 in start_thread (/lib64/libpthread.so.0+0x7593)

Move the qemu_sglist_destroy() from megasas_complete_command() to
megasas_unmap_frame(), so map/unmap are balanced.

Signed-off-by: Marc-André Lureau <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Marc-André Lureau <[email protected]>

Author: elmarco

hw/scsi/megasas.c

@@ -464,6 +464,7 @@ static void megasas_unmap_frame(MegasasState *s, MegasasCmd *cmd)
     cmd->frame = NULL;
     cmd->pa = 0;
     cmd->pa_size = 0;
+    qemu_sglist_destroy(&cmd->qsg);
     clear_bit(cmd->index, s->frame_map);
 }
 
@@ -580,7 +581,6 @@ static void megasas_complete_frame(MegasasState *s, uint64_t context)
 
 static void megasas_complete_command(MegasasCmd *cmd)
 {
-    qemu_sglist_destroy(&cmd->qsg);
     cmd->iov_size = 0;
     cmd->iov_offset = 0;