When a user does not specify a backend, a segfault can be triggered due to a strcmp() being called on a NULL char*:
$ gdb --args qemu -usb -device usb-ccid \ -device ccid-card-emulated,id=smartcard0 \ ... (gdb) s emulated_initfn (base=0x555556cb2e70) at /home/mdroth/w/qemu.git/hw/ccid-card-emulated.c:503 503 card->backend = parse_enumeration(card->backend_str, backend_enum_table, 0); (gdb) s parse_enumeration (not_found_value=0, table=0x555555b9b3c0, str=0x0) at /home/mdroth/w/qemu.git/hw/ccid-card-emulated.c:476 476 while (table->name != NULL) { (gdb) s 477 if (strcmp(table->name, str) == 0) { (gdb) s Program received signal SIGSEGV, Segmentation fault. 0x00007ffff60df09a in ?? () from /lib/x86_64-linux-gnu/libc.so.6 After the fix: $ qemu -usb -device usb-ccid \ -device ccid-card-emulated,id=smartcard0 \ ... unknown backend, must be one of: nss-emulated certificates qemu-system-x86_64: -device ccid-card-emulated,id=smartcard0,backend=nss-certificates: Device 'ccid-card-emulated' could not be initialized Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> --- hw/ccid-card-emulated.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/hw/ccid-card-emulated.c b/hw/ccid-card-emulated.c index f4a6da4..740e8df 100644 --- a/hw/ccid-card-emulated.c +++ b/hw/ccid-card-emulated.c @@ -473,6 +473,9 @@ static uint32_t parse_enumeration(char *str, { uint32_t ret = not_found_value; + if (!str) { + return ret; + } while (table->name != NULL) { if (strcmp(table->name, str) == 0) { ret = table->value; -- 1.7.9.5