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scsi: fix buffer overflow in scsi_req_parse_cdb (CVE-2015-5158)
This is a guest-triggerable buffer overflow present in QEMU 2.2.0
and newer.  scsi_cdb_length returns -1 as an error value, but the
caller does not check it.

Luckily, the massive overflow means that QEMU will just SIGSEGV,
making the impact much smaller.

Reported-by: Zhu Donghai (朱东海) <donghai.zdh@alibaba-inc.com>
Fixes: 1894df0
Reviewed-by: Fam Zheng <famz@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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bonzini committed Jul 24, 2015
1 parent 6092845 commit c170aad
Showing 1 changed file with 6 additions and 1 deletion.
7 changes: 6 additions & 1 deletion hw/scsi/scsi-bus.c
Expand Up @@ -1239,10 +1239,15 @@ int scsi_cdb_length(uint8_t *buf) {
int scsi_req_parse_cdb(SCSIDevice *dev, SCSICommand *cmd, uint8_t *buf)
{
int rc;
int len;

cmd->lba = -1;
cmd->len = scsi_cdb_length(buf);
len = scsi_cdb_length(buf);
if (len < 0) {
return -1;
}

cmd->len = len;
switch (dev->type) {
case TYPE_TAPE:
rc = scsi_req_stream_xfer(cmd, dev, buf);
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