Commit d4cdc46c authored by Ben Hutchings's avatar Ben Hutchings Committed by Kalle Valo
Browse files

wifi: iwlegacy: Fix "field-spanning write" warning in il_enqueue_hcmd() 



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: default avatarMartin-Éric Racine <martin-eric.racine@iki.fi>
References: https://bugs.debian.org/1062421
References: https://bugzilla.kernel.org/show_bug.cgi?id=219124


Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
Fixes: 54d9469b ("fortify: Add run-time WARN for cross-field memcpy()")
Tested-by: default avatarMartin-Éric Racine <martin-eric.racine@iki.fi>
Tested-by: default avatarBrandon Nielsen <nielsenb@jetfuse.net>
Acked-by: default avatarStanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: default avatarKalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/ZuIhQRi/791vlUhE@decadent.org.uk
parent 34b69548

drivers/net/wireless/intel/iwlegacy/common.c

+12 −1
Original line number Diff line number Diff line
@@ -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 */

drivers/net/wireless/intel/iwlegacy/common.h

+12 −0
Original line number Diff line number Diff line
@@ -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;