From: Mahesh J Salgaonkar <mahesh@linux.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: jniethe5@gmail.com, linuxppc-dev@lists.ozlabs.org, joel@jms.id.au
Subject: Re: [PATCH 1/2] powerpc/powernv: Fix fortify source warnings in opal-prd.c
Date: Wed, 23 Aug 2023 08:28:16 +0530 [thread overview]
Message-ID: <bssbc544h5dnd4ptlcdm7rul2kggxxoh4nxvludl4pelnskb56@7hb2feitzu7o> (raw)
In-Reply-To: <20230821142820.497107-1-mpe@ellerman.id.au>
On 2023-08-22 00:28:19 Tue, Michael Ellerman wrote:
> As reported by Mahesh & Aneesh, opal_prd_msg_notifier() triggers a
> FORTIFY_SOURCE warning:
>
> memcpy: detected field-spanning write (size 32) of single field "&item->msg" at arch/powerpc/platforms/powernv/opal-prd.c:355 (size 4)
> WARNING: CPU: 9 PID: 660 at arch/powerpc/platforms/powernv/opal-prd.c:355 opal_prd_msg_notifier+0x174/0x188 [opal_prd]
> NIP opal_prd_msg_notifier+0x174/0x188 [opal_prd]
> LR opal_prd_msg_notifier+0x170/0x188 [opal_prd]
> Call Trace:
> opal_prd_msg_notifier+0x170/0x188 [opal_prd] (unreliable)
> notifier_call_chain+0xc0/0x1b0
> atomic_notifier_call_chain+0x2c/0x40
> opal_message_notify+0xf4/0x2c0
>
> This happens because the copy is targetting item->msg, which is only 4
> bytes in size, even though the enclosing item was allocated with extra
> space following the msg.
>
> To fix the warning define struct opal_prd_msg with a union of the header
> and a flex array, and have the memcpy target the flex array.
>
> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Reported-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Thanks,
-Mahesh
> ---
> arch/powerpc/platforms/powernv/opal-prd.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-prd.c b/arch/powerpc/platforms/powernv/opal-prd.c
> index 113bdb151f68..40e26e9f318f 100644
> --- a/arch/powerpc/platforms/powernv/opal-prd.c
> +++ b/arch/powerpc/platforms/powernv/opal-prd.c
> @@ -24,13 +24,20 @@
> #include <linux/uaccess.h>
>
>
> +struct opal_prd_msg {
> + union {
> + struct opal_prd_msg_header header;
> + DECLARE_FLEX_ARRAY(u8, data);
> + };
> +};
> +
> /*
> * The msg member must be at the end of the struct, as it's followed by the
> * message data.
> */
> struct opal_prd_msg_queue_item {
> - struct list_head list;
> - struct opal_prd_msg_header msg;
> + struct list_head list;
> + struct opal_prd_msg msg;
> };
>
> static struct device_node *prd_node;
> @@ -156,7 +163,7 @@ static ssize_t opal_prd_read(struct file *file, char __user *buf,
> int rc;
>
> /* we need at least a header's worth of data */
> - if (count < sizeof(item->msg))
> + if (count < sizeof(item->msg.header))
> return -EINVAL;
>
> if (*ppos)
> @@ -186,7 +193,7 @@ static ssize_t opal_prd_read(struct file *file, char __user *buf,
> return -EINTR;
> }
>
> - size = be16_to_cpu(item->msg.size);
> + size = be16_to_cpu(item->msg.header.size);
> if (size > count) {
> err = -EINVAL;
> goto err_requeue;
> @@ -352,7 +359,7 @@ static int opal_prd_msg_notifier(struct notifier_block *nb,
> if (!item)
> return -ENOMEM;
>
> - memcpy(&item->msg, msg->params, msg_size);
> + memcpy(&item->msg.data, msg->params, msg_size);
>
> spin_lock_irqsave(&opal_prd_msg_queue_lock, flags);
> list_add_tail(&item->list, &opal_prd_msg_queue);
> --
> 2.41.0
>
--
Mahesh J Salgaonkar
next prev parent reply other threads:[~2023-08-23 2:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-21 14:28 [PATCH 1/2] powerpc/powernv: Fix fortify source warnings in opal-prd.c Michael Ellerman
2023-08-21 14:28 ` [PATCH 2/2] powerpc/powernv: Use struct opal_prd_msg in more places Michael Ellerman
2023-08-23 2:58 ` Mahesh J Salgaonkar [this message]
2023-08-31 4:02 ` [PATCH 1/2] powerpc/powernv: Fix fortify source warnings in opal-prd.c Michael Ellerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bssbc544h5dnd4ptlcdm7rul2kggxxoh4nxvludl4pelnskb56@7hb2feitzu7o \
--to=mahesh@linux.ibm.com \
--cc=jniethe5@gmail.com \
--cc=joel@jms.id.au \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.