Re: [PATCH 6.11 009/245] wifi: iwlegacy: Fix "field-spanning write" warning in il_enqueue_hcmd()

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Applies cleanly to 6.11.6 and fixes the kernel oops.

ke 6. marrask. 2024 klo 14.26 Greg Kroah-Hartman
(gregkh@xxxxxxxxxxxxxxxxxxx) kirjoitti:
>
> 6.11-stable review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
>
> [ Upstream commit d4cdc46ca16a5c78b36c5b9b6ad8cac09d6130a0 ]
>
> iwlegacy uses command buffers with a payload size of 320
> bytes (default) or 4092 bytes (huge).  The struct il_device_cmd type
> describes the default buffers and there is no separate type describing
> the huge buffers.
>
> The il_enqueue_hcmd() function works with both default and huge
> buffers, and has a memcpy() to the buffer payload.  The size of
> this copy may exceed 320 bytes when using a huge buffer, which
> now results in a run-time warning:
>
>     memcpy: detected field-spanning write (size 1014) of single field "&out_cmd->cmd.payload" at drivers/net/wireless/intel/iwlegacy/common.c:3170 (size 320)
>
> To fix this:
>
> - Define a new struct type for huge buffers, with a correctly sized
>   payload field
> - When using a huge buffer in il_enqueue_hcmd(), cast the command
>   buffer pointer to that type when looking up the payload field
>
> Reported-by: Martin-Éric Racine <martin-eric.racine@xxxxxx>
> References: https://bugs.debian.org/1062421
> References: https://bugzilla.kernel.org/show_bug.cgi?id=219124
> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> Fixes: 54d9469bc515 ("fortify: Add run-time WARN for cross-field memcpy()")
> Tested-by: Martin-Éric Racine <martin-eric.racine@xxxxxx>
> Tested-by: Brandon Nielsen <nielsenb@xxxxxxxxxxx>
> Acked-by: Stanislaw Gruszka <stf_xl@xxxxx>
> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxx>
> Link: https://patch.msgid.link/ZuIhQRi/791vlUhE@xxxxxxxxxxxxxxx
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  drivers/net/wireless/intel/iwlegacy/common.c | 13 ++++++++++++-
>  drivers/net/wireless/intel/iwlegacy/common.h | 12 ++++++++++++
>  2 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/intel/iwlegacy/common.c b/drivers/net/wireless/intel/iwlegacy/common.c
> index 9d33a66a49b59..4616293ec0cf4 100644
> --- a/drivers/net/wireless/intel/iwlegacy/common.c
> +++ b/drivers/net/wireless/intel/iwlegacy/common.c
> @@ -3122,6 +3122,7 @@ il_enqueue_hcmd(struct il_priv *il, struct il_host_cmd *cmd)
>         struct il_cmd_meta *out_meta;
>         dma_addr_t phys_addr;
>         unsigned long flags;
> +       u8 *out_payload;
>         u32 idx;
>         u16 fix_size;
>
> @@ -3157,6 +3158,16 @@ il_enqueue_hcmd(struct il_priv *il, struct il_host_cmd *cmd)
>         out_cmd = txq->cmd[idx];
>         out_meta = &txq->meta[idx];
>
> +       /* The payload is in the same place in regular and huge
> +        * command buffers, but we need to let the compiler know when
> +        * we're using a larger payload buffer to avoid "field-
> +        * spanning write" warnings at run-time for huge commands.
> +        */
> +       if (cmd->flags & CMD_SIZE_HUGE)
> +               out_payload = ((struct il_device_cmd_huge *)out_cmd)->cmd.payload;
> +       else
> +               out_payload = out_cmd->cmd.payload;
> +
>         if (WARN_ON(out_meta->flags & CMD_MAPPED)) {
>                 spin_unlock_irqrestore(&il->hcmd_lock, flags);
>                 return -ENOSPC;
> @@ -3170,7 +3181,7 @@ il_enqueue_hcmd(struct il_priv *il, struct il_host_cmd *cmd)
>                 out_meta->callback = cmd->callback;
>
>         out_cmd->hdr.cmd = cmd->id;
> -       memcpy(&out_cmd->cmd.payload, cmd->data, cmd->len);
> +       memcpy(out_payload, cmd->data, cmd->len);
>
>         /* At this point, the out_cmd now has all of the incoming cmd
>          * information */
> diff --git a/drivers/net/wireless/intel/iwlegacy/common.h b/drivers/net/wireless/intel/iwlegacy/common.h
> index 69687fcf963fc..027dae5619a37 100644
> --- a/drivers/net/wireless/intel/iwlegacy/common.h
> +++ b/drivers/net/wireless/intel/iwlegacy/common.h
> @@ -560,6 +560,18 @@ struct il_device_cmd {
>
>  #define TFD_MAX_PAYLOAD_SIZE (sizeof(struct il_device_cmd))
>
> +/**
> + * struct il_device_cmd_huge
> + *
> + * For use when sending huge commands.
> + */
> +struct il_device_cmd_huge {
> +       struct il_cmd_header hdr;       /* uCode API */
> +       union {
> +               u8 payload[IL_MAX_CMD_SIZE - sizeof(struct il_cmd_header)];
> +       } __packed cmd;
> +} __packed;
> +
>  struct il_host_cmd {
>         const void *data;
>         unsigned long reply_page;
> --
> 2.43.0
>
>
>





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