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Subject[PATCH 5.15 04/42] RDMA/mlx5: Fix releasing unallocated memory in dereg MR flow
Date
From: Alaa Hleihel <alaa@nvidia.com>

[ Upstream commit f0ae4afe3d35e67db042c58a52909e06262b740f ]

For the case of IB_MR_TYPE_DM the mr does doesn't have a umem, even though
it is a user MR. This causes function mlx5_free_priv_descs() to think that
it is a kernel MR, leading to wrongly accessing mr->descs that will get
wrong values in the union which leads to attempt to release resources that
were not allocated in the first place.

For example:
DMA-API: mlx5_core 0000:08:00.1: device driver tries to free DMA memory it has not allocated [device address=0x0000000000000000] [size=0 bytes]
WARNING: CPU: 8 PID: 1021 at kernel/dma/debug.c:961 check_unmap+0x54f/0x8b0
RIP: 0010:check_unmap+0x54f/0x8b0
Call Trace:
debug_dma_unmap_page+0x57/0x60
mlx5_free_priv_descs+0x57/0x70 [mlx5_ib]
mlx5_ib_dereg_mr+0x1fb/0x3d0 [mlx5_ib]
ib_dereg_mr_user+0x60/0x140 [ib_core]
uverbs_destroy_uobject+0x59/0x210 [ib_uverbs]
uobj_destroy+0x3f/0x80 [ib_uverbs]
ib_uverbs_cmd_verbs+0x435/0xd10 [ib_uverbs]
? uverbs_finalize_object+0x50/0x50 [ib_uverbs]
? lock_acquire+0xc4/0x2e0
? lock_acquired+0x12/0x380
? lock_acquire+0xc4/0x2e0
? lock_acquire+0xc4/0x2e0
? ib_uverbs_ioctl+0x7c/0x140 [ib_uverbs]
? lock_release+0x28a/0x400
ib_uverbs_ioctl+0xc0/0x140 [ib_uverbs]
? ib_uverbs_ioctl+0x7c/0x140 [ib_uverbs]
__x64_sys_ioctl+0x7f/0xb0
do_syscall_64+0x38/0x90

Fix it by reorganizing the dereg flow and mlx5_ib_mr structure:
- Move the ib_umem field into the user MRs structure in the union as it's
applicable only there.
- Function mlx5_ib_dereg_mr() will now call mlx5_free_priv_descs() only
in case there isn't udata, which indicates that this isn't a user MR.

Fixes: f18ec4223117 ("RDMA/mlx5: Use a union inside mlx5_ib_mr")
Link: https://lore.kernel.org/r/66bb1dd253c1fd7ceaa9fc411061eefa457b86fb.1637581144.git.leonro@nvidia.com
Signed-off-by: Alaa Hleihel <alaa@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/hw/mlx5/mlx5_ib.h | 6 +++---
drivers/infiniband/hw/mlx5/mr.c | 26 ++++++++++++--------------
2 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index bf20a388eabe1..6204ae2caef58 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -641,7 +641,6 @@ struct mlx5_ib_mr {

/* User MR data */
struct mlx5_cache_ent *cache_ent;
- struct ib_umem *umem;

/* This is zero'd when the MR is allocated */
union {
@@ -653,7 +652,7 @@ struct mlx5_ib_mr {
struct list_head list;
};

- /* Used only by kernel MRs (umem == NULL) */
+ /* Used only by kernel MRs */
struct {
void *descs;
void *descs_alloc;
@@ -675,8 +674,9 @@ struct mlx5_ib_mr {
int data_length;
};

- /* Used only by User MRs (umem != NULL) */
+ /* Used only by User MRs */
struct {
+ struct ib_umem *umem;
unsigned int page_shift;
/* Current access_flags */
int access_flags;
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 22e2f4d79743d..69b2ce4c292ae 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1911,19 +1911,18 @@ mlx5_alloc_priv_descs(struct ib_device *device,
return ret;
}

-static void
-mlx5_free_priv_descs(struct mlx5_ib_mr *mr)
+static void mlx5_free_priv_descs(struct mlx5_ib_mr *mr)
{
- if (!mr->umem && mr->descs) {
- struct ib_device *device = mr->ibmr.device;
- int size = mr->max_descs * mr->desc_size;
- struct mlx5_ib_dev *dev = to_mdev(device);
+ struct mlx5_ib_dev *dev = to_mdev(mr->ibmr.device);
+ int size = mr->max_descs * mr->desc_size;

- dma_unmap_single(&dev->mdev->pdev->dev, mr->desc_map, size,
- DMA_TO_DEVICE);
- kfree(mr->descs_alloc);
- mr->descs = NULL;
- }
+ if (!mr->descs)
+ return;
+
+ dma_unmap_single(&dev->mdev->pdev->dev, mr->desc_map, size,
+ DMA_TO_DEVICE);
+ kfree(mr->descs_alloc);
+ mr->descs = NULL;
}

int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
@@ -1999,7 +1998,8 @@ int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
if (mr->cache_ent) {
mlx5_mr_cache_free(dev, mr);
} else {
- mlx5_free_priv_descs(mr);
+ if (!udata)
+ mlx5_free_priv_descs(mr);
kfree(mr);
}
return 0;
@@ -2086,7 +2086,6 @@ static struct mlx5_ib_mr *mlx5_ib_alloc_pi_mr(struct ib_pd *pd,
if (err)
goto err_free_in;

- mr->umem = NULL;
kfree(in);

return mr;
@@ -2213,7 +2212,6 @@ static struct ib_mr *__mlx5_ib_alloc_mr(struct ib_pd *pd,
}

mr->ibmr.device = pd->device;
- mr->umem = NULL;

switch (mr_type) {
case IB_MR_TYPE_MEM_REG:
--
2.33.0


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