From: Todd Poynor <toddpoynor@xxxxxxxxxx>
This patch has been added to the v4.1 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 8d26f491116feaa0b16de370b6a7ba40a40fa0b4 ]
Commit 1bc0eb044615 ("scsi: sg: protect accesses to 'reserved' page
array") adds needed concurrency protection for the "reserve" buffer.
Some checks that are initially made outside the lock are replicated once
the lock is taken to ensure the checks and resulting decisions are made
using consistent state.
The check that a request with flag SG_FLAG_MMAP_IO set fits in the
reserve buffer also needs to be performed again under the lock to ensure
the reserve buffer length compared against matches the value in effect
when the request is linked to the reserve buffer. An -ENOMEM should be
returned in this case, instead of switching over to an indirect buffer
as for non-MMAP_IO requests.
Signed-off-by: Todd Poynor <toddpoynor@xxxxxxxxxx>
Acked-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
drivers/scsi/sg.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 1defc26a4072..ac6cf3ccf423 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1751,9 +1751,12 @@ sg_start_req(Sg_request *srp, unsigned char *cmd)
!sfp->res_in_use) {
sfp->res_in_use = 1;
sg_link_reserve(sfp, srp, dxfer_len);
- } else if ((hp->flags & SG_FLAG_MMAP_IO) && sfp->res_in_use) {
+ } else if (hp->flags & SG_FLAG_MMAP_IO) {
+ res = -EBUSY; /* sfp->res_in_use == 1 */
+ if (dxfer_len > rsv_schp->bufflen)
+ res = -ENOMEM;
mutex_unlock(&sfp->f_mutex);
- return -EBUSY;
+ return res;
} else {
res = sg_build_indirect(req_schp, sfp, dxfer_len);
if (res) {
--
2.11.0