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authorPetr Uzel <petr.uzel@suse.cz>2011-10-21 13:31:09 +0200
committerJames Bottomley <JBottomley@Parallels.com>2011-10-30 13:27:28 +0400
commitc68bf8eeaa57c852e74adcf597237be149eef830 (patch)
treebd631c9731acc98e562fe202da55b050637c203f /drivers/scsi/st.c
parent3308511c93e6ad0d3c58984ecd6e5e57f96b12c8 (diff)
[SCSI] st: fix race in st_scsi_execute_end
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. CC: stable@kernel.org 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>
Diffstat (limited to 'drivers/scsi/st.c')
-rw-r--r--drivers/scsi/st.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 1871b8ae83ae..9b28f39bac26 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -462,14 +462,16 @@ static void st_scsi_execute_end(struct request *req, int uptodate)
{
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);
}