From: Michael Ellerman <mpe@ellerman.id.au>
To: <linuxppc-dev@lists.ozlabs.org>
Cc: jniethe5@gmail.com, mahesh@linux.ibm.com, joel@jms.id.au
Subject: [PATCH 1/2] powerpc/powernv: Fix fortify source warnings in opal-prd.c
Date: Tue, 22 Aug 2023 00:28:19 +1000 [thread overview]
Message-ID: <20230821142820.497107-1-mpe@ellerman.id.au> (raw)
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>
---
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
next reply other threads:[~2023-08-21 14:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-21 14:28 Michael Ellerman [this message]
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 ` [PATCH 1/2] powerpc/powernv: Fix fortify source warnings in opal-prd.c Mahesh J Salgaonkar
2023-08-31 4:02 ` Michael Ellerman
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