* [PATCH AUTOSEL 5.4 10/10] net/rds: dma_map_sg is entitled to merge entries
[not found] <20210824005458.631377-1-sashal@kernel.org>
@ 2021-08-24 0:54 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2021-08-24 0:54 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Gerd Rausch, Santosh Shilimkar, Jakub Kicinski, Sasha Levin,
netdev, linux-rdma, rds-devel
From: Gerd Rausch <gerd.rausch@oracle.com>
[ Upstream commit fb4b1373dcab086d0619c29310f0466a0b2ceb8a ]
Function "dma_map_sg" is entitled to merge adjacent entries
and return a value smaller than what was passed as "nents".
Subsequently "ib_map_mr_sg" needs to work with this value ("sg_dma_len")
rather than the original "nents" parameter ("sg_len").
This old RDS bug was exposed and reliably causes kernel panics
(using RDMA operations "rds-stress -D") on x86_64 starting with:
commit c588072bba6b ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
Simply put: Linux 5.11 and later.
Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Link: https://lore.kernel.org/r/60efc69f-1f35-529d-a7ef-da0549cad143@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/rds/ib_frmr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/rds/ib_frmr.c b/net/rds/ib_frmr.c
index 06ecf9d2d4bf..ef6acd721118 100644
--- a/net/rds/ib_frmr.c
+++ b/net/rds/ib_frmr.c
@@ -131,9 +131,9 @@ static int rds_ib_post_reg_frmr(struct rds_ib_mr *ibmr)
cpu_relax();
}
- ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_len,
+ ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_dma_len,
&off, PAGE_SIZE);
- if (unlikely(ret != ibmr->sg_len))
+ if (unlikely(ret != ibmr->sg_dma_len))
return ret < 0 ? ret : -EINVAL;
if (cmpxchg(&frmr->fr_state,
--
2.30.2
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2021-08-24 0:54 ` [PATCH AUTOSEL 5.4 10/10] net/rds: dma_map_sg is entitled to merge entries Sasha Levin
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