| From c68bf8eeaa57c852e74adcf597237be149eef830 Mon Sep 17 00:00:00 2001 |
| From: Petr Uzel <petr.uzel@suse.cz> |
| Date: Fri, 21 Oct 2011 13:31:09 +0200 |
| Subject: [SCSI] st: fix race in st_scsi_execute_end |
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| |
| From: Petr Uzel <petr.uzel@suse.cz> |
| |
| commit c68bf8eeaa57c852e74adcf597237be149eef830 upstream. |
| |
| The call to complete() in st_scsi_execute_end() wakes up sleeping thread |
| in write_behind_check(), which frees the st_request, thus invalidating |
| the pointer to the associated bio structure, which is then passed to the |
| blk_rq_unmap_user(). Fix by storing pointer to bio structure into |
| temporary local variable. |
| |
| This bug is present since at least linux-2.6.32. |
| |
| Signed-off-by: Petr Uzel <petr.uzel@suse.cz> |
| Reported-by: Juergen Groß <juergen.gross@ts.fujitsu.com> |
| Reviewed-by: Jan Kara <jack@suse.cz> |
| Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi> |
| Signed-off-by: James Bottomley <JBottomley@Parallels.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| drivers/scsi/st.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/scsi/st.c |
| +++ b/drivers/scsi/st.c |
| @@ -462,14 +462,16 @@ static void st_scsi_execute_end(struct r |
| { |
| struct st_request *SRpnt = req->end_io_data; |
| struct scsi_tape *STp = SRpnt->stp; |
| + struct bio *tmp; |
| |
| STp->buffer->cmdstat.midlevel_result = SRpnt->result = req->errors; |
| STp->buffer->cmdstat.residual = req->resid_len; |
| |
| + tmp = SRpnt->bio; |
| if (SRpnt->waiting) |
| complete(SRpnt->waiting); |
| |
| - blk_rq_unmap_user(SRpnt->bio); |
| + blk_rq_unmap_user(tmp); |
| __blk_put_request(req->q, req); |
| } |
| |
