[PATCH] nvme: Report MDTS values that are too large

[PATCH] nvme: Report MDTS values that are too large

[Bart Van Assche]

Instead of triggering an integer overflow and undefined behavior if MDTS is
too large, set max_hw_sectors to UINT_MAX and log an error message.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/nvme/host/core.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 40215a0246e4..0edbc8c125a7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3123,10 +3123,14 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
 
 	atomic_set(&ctrl->abort_limit, id->acl + 1);
 	ctrl->vwc = id->vwc;
-	if (id->mdts)
-		max_hw_sectors = 1 << (id->mdts + page_shift - 9);
-	else
+	max_hw_sectors = UINT_MAX;
+	if (id->mdts && check_shl_overflow(1U, id->mdts + page_shift - 9,
+					   &max_hw_sectors)) {
+		dev_err(ctrl->device,
+			"MDTS = %u is too large (page_shift = %u)\n",
+			id->mdts, page_shift);
 		max_hw_sectors = UINT_MAX;
+	}
 	ctrl->max_hw_sectors =
 		min_not_zero(ctrl->max_hw_sectors, max_hw_sectors);
 

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Re: [PATCH] nvme: Report MDTS values that are too large

[Christoph Hellwig]

On Tue, Mar 30, 2021 at 08:42:14PM -0700, Bart Van Assche wrote:
> Instead of triggering an integer overflow and undefined behavior if MDTS is
> too large, set max_hw_sectors to UINT_MAX and log an error message.

I really do not think reporting an error for something that is
perfetly valid but not useful to Linux makes much sense.

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