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scsi: target/iblock: Fix overrun in WRITE SAME emulation

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WRITE SAME corrupts data on the block device behind iblock if the command
is emulated. The emulation code issues (M - 1) * N times more bios than
requested, where M is the number of 512 blocks per real block size and N is
the NUMBER OF LOGICAL BLOCKS specified in WRITE SAME command. So, for a
device with 4k blocks, 7 * N more LBAs gets written after the requested
range.

The issue happens because the number of 512 byte sectors to be written is
decreased one by one while the real bios are typically from 1 to 8 512 byte
sectors per bio.

Fixes: c66ac9db8d ("[SCSI] target: Add LIO target core v4.0.0-rc6")
Cc: <stable@vger.kernel.org>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Roman Bolshakov 2019-07-02 22:16:38 +03:00 committed by Martin K. Petersen
parent 240b4cc8fd
commit 5676234f20
1 changed files with 1 additions and 1 deletions
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2
drivers/target/target_core_iblock.c
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@ -515,7 +515,7 @@ iblock_execute_write_same(struct se_cmd *cmd)
/* Always in 512 byte units for Linux/Block */
block_lba += sg->length >> SECTOR_SHIFT;
sectors -= 1;
sectors -= sg->length >> SECTOR_SHIFT;
}
iblock_submit_bios(&list);