[stgt] [PATCH] Another patch to improve the LBA out of range even further

[ronnie sahlberg]

List, Tomo

Please find another patch to improve the LBA out of range checks even more.
We shouldnt shift the LBA << 9 and compare with file size since if the
initiator used a HUGE LBA,
(for example 0x8000000000000000ULL)  then this shift makes the LBA 0
and the i/o is successful.

Instead we should shift the filesize >> 9 before the compare so that
we dont risk overflowing this 64 bit integer.


We also need to check for if a HUGE LBA and the TL will wrap.
For example if the LBA is 0xffffffffffffffff and the tl is 2, then LBA
+ TL wraps and becomes 1  so the i/o will fail the LBA out of range
check.
To handle this case too I added a check for this explicit wrap  lba+tl < lba'



These tests are available in the iscsi/scsi test tool in libiscsi for
those interested.
I have already seen several other targets that also seems to do LBA<<9
for the check and thus fail in the 'read from LBA2^63' test. Fail as
in returning the data from LBA:0 instead of a lba-out-of-range
check-condition.


/bin/iscsi-test --test='*read16_beyond*' iscsi://127.0.0.1/iqn.ronnie.test/1
0204_read16_beyond_eol:
=======================
Reading 1-256 blocks beyond end-of-device ... [OK]
Reading 1-256 blocks at LBA 2^63 ... [OK]
Reading 1-256 blocks at LBA -1 ... [OK]
TEST T0204_read16_beyondeol [OK]


regards
ronnie sahlberg
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