| Date | Wed, 09 Nov 2011 13:34:20 -0800 | From | Greg KH <> | Subject | [213/264] [SCSI] st: fix race in st_scsi_execute_end |
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3.1-stable review patch. If anyone has any objections, please let me know.
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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 Groà <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); }
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