Commit bdb2b8ca authored Jun 24, 2008 by Alan Stern Committed by James Bottomley Jul 06, 2008

[SCSI] erase invalid data returned by device



This patch (as1108) fixes a problem that can occur with certain USB
mass-storage devices: They return invalid data together with a residue
indicating that the data should be ignored.  Rather than leave the
invalid data in a transfer buffer, where it can get misinterpreted,
the patch clears the invalid portion of the buffer.

This solves a problem (wrong write-protect setting detected) reported
by Maciej Rutecki and Peter Teoh.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Peter Teoh <htmldeveloper@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

parent b7279469

drivers/scsi/scsi_lib.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -207,6 +207,15 @@ int scsi_execute(struct scsi_device sdev, const unsigned char cmd,
		*/
		blk_execute_rq(req->q, NULL, req, 1);

		/*
		* Some devices (USB mass-storage in particular) may transfer
		* garbage data together with a residue indicating that the data
		* is invalid. Prevent the garbage from being misinterpreted
		* and prevent security leaks by zeroing out the excess data.
		*/
		if (unlikely(req->data_len > 0 && req->data_len <= bufflen))
		memset(buffer + (bufflen - req->data_len), 0, req->data_len);

		ret = req->errors;
		out:
		blk_put_request(req);

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