[Qemu-devel] [PATCH] SCSI improved LBA-out-of-range checks BUGFIX

[Qemu-devel] [PATCH] SCSI improved LBA-out-of-range checks BUGFIX

[Ronnie Sahlberg]

Paolo,

Sorry but the previous patch was bad.
Use this patch instead it uses the correct check of
        if (r->req.cmd.lba > r->req.cmd.lba + len
        ||  r->req.cmd.lba + len > s->qdev.max_lba + 1) {

[Qemu-devel] [PATCH] SCSI Improved checking for LBA out of range

[Ronnie Sahlberg]

Improve the tests for the LBA to cover more cases, the new test looks like this
        if (r->req.cmd.lba > r->req.cmd.lba + len
        ||  r->req.cmd.lba + len > s->qdev.max_lba + 1) {

For the 16 byte opcodes, the lba is a uint64, so the first check is to make sure that we do not wrap.
For example if an opcode would specify the LBA:0xffffffffffffffff and LEN:2
then lba+len would wrap to 1.

The second part of the test is to verify that ALL requested blocks are available, not just the first one.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
---
 hw/scsi-disk.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index b2f3c0c..2c2be33 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -1558,7 +1558,8 @@ static int32_t scsi_send_command(SCSIRequest *req, uint8_t *buf)
         if (r->req.cmd.buf[1] & 0xe0) {
             goto fail;
         }
-        if (r->req.cmd.lba > s->qdev.max_lba) {
+        if (r->req.cmd.lba > r->req.cmd.lba + len
+        ||  r->req.cmd.lba + len > s->qdev.max_lba + 1) {
             goto illegal_lba;
         }
         r->sector = r->req.cmd.lba * (s->qdev.blocksize / 512);
@@ -1581,7 +1582,8 @@ static int32_t scsi_send_command(SCSIRequest *req, uint8_t *buf)
         if (r->req.cmd.buf[1] & 0xe0) {
             goto fail;
         }
-        if (r->req.cmd.lba > s->qdev.max_lba) {
+        if (r->req.cmd.lba > r->req.cmd.lba + len
+        ||  r->req.cmd.lba + len > s->qdev.max_lba + 1) {
             goto illegal_lba;
         }
         r->sector = r->req.cmd.lba * (s->qdev.blocksize / 512);
-- 
1.7.3.1