[PATCH] nvme-pci: fix out-of-bounds access in nvme_setup_descriptor_pools

[Caleb Sander Mateos]

On Fri, May 22, 2026 at 8:07 AM Mateusz Nowicki
<mateusz.nowicki at posteo.net> wrote:
>
> nvme_setup_descriptor_pools() indexes dev->descriptor_pools[] using the
> numa_node forwarded from hctx->numa_node by its single caller,
> nvme_init_hctx_common().  On a non-NUMA kernel hctx->numa_node is
> NUMA_NO_NODE (-1).  Because the parameter was declared 'unsigned', the
> value becomes UINT_MAX and the index walks off the array (sized to
> nr_node_ids), faulting during nvme_alloc_ns() and leaving the namespace
> without a /dev node.

FYI there was a previous report and patch for this issue:
https://lore.kernel.org/linux-nvme/20260309062840.2937858-2-iam@sung-woo.kim/T/#u
. Looks like a v2 was promised but never arrived. Some attribution
(Reported-by, Link?) for the original patch might be good.

I did like that the other patch switched the type of struct
blk_mq_hw_ctx's numa_node field and the argument to struct
blk_mq_ops's init_request function pointer from unsigned int to int to
clarify that it was optional. But probably makes sense to do that as a
follow-on commit separate from the bug fix.

>
> Reproduces on any NVMe controller probed by a CONFIG_NUMA=n kernel
>
>   BUG: unable to handle page fault for address: ffff889101603d38
>   RIP: 0010:nvme_init_hctx_common+0x5a/0x190 [nvme]
>   Call Trace:
>    nvme_init_hctx+0x10/0x20 [nvme]
>    nvme_alloc_ns+0x9e/0xa10 [nvme_core]
>    nvme_scan_ns+0x301/0x3b0 [nvme_core]
>    nvme_scan_ns_async+0x23/0x30 [nvme_core]
>
> Switch the parameter to int and fall back to node 0 for negative or
> out-of-range values; node 0 is always present.
>
> Signed-off-by: Mateusz Nowicki <mateusz.nowicki at posteo.net>
> ---
>  drivers/nvme/host/pci.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 9fd04cd7c5cb..ecec0f9cff98 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -587,11 +587,17 @@ static bool nvme_dbbuf_update_and_check_event(u16 value, __le32 *dbbuf_db,
>  }
>
>  static struct nvme_descriptor_pools *
> -nvme_setup_descriptor_pools(struct nvme_dev *dev, unsigned numa_node)
> +nvme_setup_descriptor_pools(struct nvme_dev *dev, int numa_node)
>  {
> -       struct nvme_descriptor_pools *pools = &dev->descriptor_pools[numa_node];
> +       struct nvme_descriptor_pools *pools;
>         size_t small_align = NVME_SMALL_POOL_SIZE;
>
> +       /* hctx->numa_node may be NUMA_NO_NODE; fall back to node 0. */
> +       if (numa_node < 0 || numa_node >= nr_node_ids)

Is numa_node >= nr_node_ids possible? I think just numa_node < 0
should be fine, and would avoid a compiler warning about comparing int
to unsigned int.

Best,
Caleb

> +               numa_node = 0;
> +
> +       pools = &dev->descriptor_pools[numa_node];
> +
>         if (pools->small)
>                 return pools; /* already initialized */
>
> --
> 2.53.0
>
>