[Qemu-devel] [PATCH 0/1] qemu/nbd: fix segmentation fault when .desc is not null-terminated

[Murilo Opsfelder Araujo <muriloo@linux.vnet.ibm.com>]

Hello, QEMU community.

The following patch is to fix a segmentation fault when nbd_runtime_opts.desc is
not null-terminated.

This issue emerged when building QEMU with --enable-gcov, as described by
https://bugs.launchpad.net/qemu/+bug/1727259.

To reproduce on ppc64le, run the following commands on QEMU git tree:

mkdir build
mkdir -p tests/qemu-iotests/scratch
cd build
../configure --target-list=ppc64-softmmu --enable-gcov
make -j$(nproc)

./qemu-img create -f qcow2 -o compat=1.1 ./tests/qemu-iotests/scratch/t.qcow2 64M
./qemu-io --cache writeback -f qcow2 -c "write -P 0xa 0x1000 0x1000" ./tests/qemu-iotests/scratch/t.qcow2
./qemu-io --cache writeback -f qcow2 -c "write -P 0xb 0x2000 0x1000" ./tests/qemu-iotests/scratch/t.qcow2
./qemu-img snapshot -c sn1 ./tests/qemu-iotests/scratch/t.qcow2
./qemu-io --cache writeback -f qcow2 -c "write -P 0xc 0x1000 0x1000" ./tests/qemu-iotests/scratch/t.qcow2
./qemu-io --cache writeback -f qcow2 -c "write -P 0xd 0x2000 0x1000" ./tests/qemu-iotests/scratch/t.qcow2
./qemu-img check -f qcow2 ./tests/qemu-iotests/scratch/t.qcow2
./qemu-io --cache writeback -f qcow2 -c "read -P 0xc 0x1000 0x1000" ./tests/qemu-iotests/scratch/t.qcow2
./qemu-io --cache writeback -f qcow2 -c "read -P 0xd 0x2000 0x1000" ./tests/qemu-iotests/scratch/t.qcow2

# run in background, wait some seconds until it starts
./qemu-nbd -v -t -k ${PWD}/tests/qemu-iotests/scratch/test_qemu_nbd_socket ./tests/qemu-iotests/scratch/t.qcow2 -l sn1 &
sleep 5

# this will cause qemu-io to segfault
./qemu-io --cache writeback -f qcow2 -f raw --cache=writeback -r -c "read -P 0xa 0x1000 0x1000" nbd:unix:${PWD}/tests/qemu-iotests/scratch/test_qemu_nbd_socket

# kill qemu-nbd
kill $(pidof qemu-nbd)

Cheers
Murilo

Murilo Opsfelder Araujo (1):
  block/nbd: fix segmentation fault when .desc is not null-terminated

 block/nbd.c | 1 +
 1 file changed, 1 insertion(+)

-- 
2.14.3