| Message ID | 168776304370.89193.185568680784294524.stgit@jupiter (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powernv/opal-prd: Silence memcpy() run-time false positive warnings | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
On 26/6/23 5:04 pm, Mahesh Salgaonkar wrote: > opal_prd_msg_notifier extracts the opal prd message size from the message > header and uses it for allocating opal_prd_msg_queue_item that includes > the correct message size to be copied. However, while running under > CONFIG_FORTIFY_SOURCE=y, it triggers following run-time warning: > > [ 6458.234352] memcpy: detected field-spanning write (size 32) of single field "&item->msg" at arch/powerpc/platforms/powernv/opal-prd.c:355 (size 4) > [ 6458.234390] WARNING: CPU: 9 PID: 660 at arch/powerpc/platforms/powernv/opal-prd.c:355 opal_prd_msg_notifier+0x174/0x188 [opal_prd] > [...] > [ 6458.234709] NIP [c00800000e0c0e6c] opal_prd_msg_notifier+0x174/0x188 [opal_prd] > [ 6458.234723] LR [c00800000e0c0e68] opal_prd_msg_notifier+0x170/0x188 [opal_prd] > [ 6458.234736] Call Trace: > [ 6458.234742] [c0000002acb23c10] [c00800000e0c0e68] opal_prd_msg_notifier+0x170/0x188 [opal_prd] (unreliable) > [ 6458.234759] [c0000002acb23ca0] [c00000000019ccc0] notifier_call_chain+0xc0/0x1b0 > [ 6458.234774] [c0000002acb23d00] [c00000000019ceac] atomic_notifier_call_chain+0x2c/0x40 > [ 6458.234788] [c0000002acb23d20] [c0000000000d69b4] opal_message_notify+0xf4/0x2c0 > [...] > > Add a flexible array member to avoid false positive run-time warning. > > Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> > --- > arch/powerpc/platforms/powernv/opal-prd.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/platforms/powernv/opal-prd.c b/arch/powerpc/platforms/powernv/opal-prd.c > index 113bdb151f687..9e2c4775f75f5 100644 > --- a/arch/powerpc/platforms/powernv/opal-prd.c > +++ b/arch/powerpc/platforms/powernv/opal-prd.c > @@ -30,7 +30,10 @@ > */ > struct opal_prd_msg_queue_item { > struct list_head list; > - struct opal_prd_msg_header msg; > + union { > + struct opal_prd_msg_header msg; > + DECLARE_FLEX_ARRAY(__u8, msg_flex); > + }; > }; > > static struct device_node *prd_node; > @@ -352,7 +355,7 @@ static int opal_prd_msg_notifier(struct notifier_block *nb, > if (!item) > return -ENOMEM; > > - memcpy(&item->msg, msg->params, msg_size); > + memcpy(&item->msg_flex, msg->params, msg_size); This does silence the warning but it seems like we might be able to go a little further. What about not adding that flex array to struct opal_prd_msg_queue_item, but adding one to struct opal_prd_msg. That is what the data format actually is. So we'd have something like: struct opal_prd_msg { struct opal_prd_msg_header hdr; char msg[]; } and change things to use that instead? But that might be more trouble than it is worth, alternatively we can just do: item->msg = *hdr; memcpy((char *)item->msg + sizeof(*hdr), (char *)hdr + sizeof(*hdr), msg_size - sizeof(*hdr)); > > spin_lock_irqsave(&opal_prd_msg_queue_lock, flags); > list_add_tail(&item->list, &opal_prd_msg_queue); > > > >
On 2023-07-05 11:06:46 Wed, Jordan Niethe wrote: > > > On 26/6/23 5:04 pm, Mahesh Salgaonkar wrote: > > opal_prd_msg_notifier extracts the opal prd message size from the message > > header and uses it for allocating opal_prd_msg_queue_item that includes > > the correct message size to be copied. However, while running under > > CONFIG_FORTIFY_SOURCE=y, it triggers following run-time warning: > > > > [ 6458.234352] memcpy: detected field-spanning write (size 32) of single field "&item->msg" at arch/powerpc/platforms/powernv/opal-prd.c:355 (size 4) > > [ 6458.234390] WARNING: CPU: 9 PID: 660 at arch/powerpc/platforms/powernv/opal-prd.c:355 opal_prd_msg_notifier+0x174/0x188 [opal_prd] > > [...] > > [ 6458.234709] NIP [c00800000e0c0e6c] opal_prd_msg_notifier+0x174/0x188 [opal_prd] > > [ 6458.234723] LR [c00800000e0c0e68] opal_prd_msg_notifier+0x170/0x188 [opal_prd] > > [ 6458.234736] Call Trace: > > [ 6458.234742] [c0000002acb23c10] [c00800000e0c0e68] opal_prd_msg_notifier+0x170/0x188 [opal_prd] (unreliable) > > [ 6458.234759] [c0000002acb23ca0] [c00000000019ccc0] notifier_call_chain+0xc0/0x1b0 > > [ 6458.234774] [c0000002acb23d00] [c00000000019ceac] atomic_notifier_call_chain+0x2c/0x40 > > [ 6458.234788] [c0000002acb23d20] [c0000000000d69b4] opal_message_notify+0xf4/0x2c0 > > [...] > > > > Add a flexible array member to avoid false positive run-time warning. > > > > Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > > Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> > > --- > > arch/powerpc/platforms/powernv/opal-prd.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/arch/powerpc/platforms/powernv/opal-prd.c b/arch/powerpc/platforms/powernv/opal-prd.c > > index 113bdb151f687..9e2c4775f75f5 100644 > > --- a/arch/powerpc/platforms/powernv/opal-prd.c > > +++ b/arch/powerpc/platforms/powernv/opal-prd.c > > @@ -30,7 +30,10 @@ > > */ > > struct opal_prd_msg_queue_item { > > struct list_head list; > > - struct opal_prd_msg_header msg; > > + union { > > + struct opal_prd_msg_header msg; > > + DECLARE_FLEX_ARRAY(__u8, msg_flex); > > + }; > > }; > > static struct device_node *prd_node; > > @@ -352,7 +355,7 @@ static int opal_prd_msg_notifier(struct notifier_block *nb, > > if (!item) > > return -ENOMEM; > > - memcpy(&item->msg, msg->params, msg_size); > > + memcpy(&item->msg_flex, msg->params, msg_size); > > This does silence the warning but it seems like we might be able to go a > little further. > > What about not adding that flex array to struct opal_prd_msg_queue_item, but > adding one to struct opal_prd_msg. That is what the data format actually is. > > So we'd have something like: > > > struct opal_prd_msg { > > struct opal_prd_msg_header hdr; > > char msg[]; > > } > > > and change things to use that instead? > > But that might be more trouble than it is worth, Yup, it would cause more changes to the code elsewhere as well. > alternatively we can just > do: > > item->msg = *hdr; > memcpy((char *)item->msg + sizeof(*hdr), (char *)hdr + sizeof(*hdr), > msg_size - sizeof(*hdr)); Agree, this helps, I tried with small change to above code which also works fine. item->msg = *hdr; hdr++; memcpy((char *)&item->msg + sizeof(*hdr), hdr, msg_size - sizeof(*hdr)); Will send out v2. Thanks, -Mahesh.
diff --git a/arch/powerpc/platforms/powernv/opal-prd.c b/arch/powerpc/platforms/powernv/opal-prd.c index 113bdb151f687..9e2c4775f75f5 100644 --- a/arch/powerpc/platforms/powernv/opal-prd.c +++ b/arch/powerpc/platforms/powernv/opal-prd.c @@ -30,7 +30,10 @@ */ struct opal_prd_msg_queue_item { struct list_head list; - struct opal_prd_msg_header msg; + union { + struct opal_prd_msg_header msg; + DECLARE_FLEX_ARRAY(__u8, msg_flex); + }; }; static struct device_node *prd_node; @@ -352,7 +355,7 @@ static int opal_prd_msg_notifier(struct notifier_block *nb, if (!item) return -ENOMEM; - memcpy(&item->msg, msg->params, msg_size); + memcpy(&item->msg_flex, msg->params, msg_size); spin_lock_irqsave(&opal_prd_msg_queue_lock, flags); list_add_tail(&item->list, &opal_prd_msg_queue);
opal_prd_msg_notifier extracts the opal prd message size from the message header and uses it for allocating opal_prd_msg_queue_item that includes the correct message size to be copied. However, while running under CONFIG_FORTIFY_SOURCE=y, it triggers following run-time warning: [ 6458.234352] memcpy: detected field-spanning write (size 32) of single field "&item->msg" at arch/powerpc/platforms/powernv/opal-prd.c:355 (size 4) [ 6458.234390] WARNING: CPU: 9 PID: 660 at arch/powerpc/platforms/powernv/opal-prd.c:355 opal_prd_msg_notifier+0x174/0x188 [opal_prd] [...] [ 6458.234709] NIP [c00800000e0c0e6c] opal_prd_msg_notifier+0x174/0x188 [opal_prd] [ 6458.234723] LR [c00800000e0c0e68] opal_prd_msg_notifier+0x170/0x188 [opal_prd] [ 6458.234736] Call Trace: [ 6458.234742] [c0000002acb23c10] [c00800000e0c0e68] opal_prd_msg_notifier+0x170/0x188 [opal_prd] (unreliable) [ 6458.234759] [c0000002acb23ca0] [c00000000019ccc0] notifier_call_chain+0xc0/0x1b0 [ 6458.234774] [c0000002acb23d00] [c00000000019ceac] atomic_notifier_call_chain+0x2c/0x40 [ 6458.234788] [c0000002acb23d20] [c0000000000d69b4] opal_message_notify+0xf4/0x2c0 [...] Add a flexible array member to avoid false positive run-time warning. Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> --- arch/powerpc/platforms/powernv/opal-prd.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)