[PATCH] PCI: octep: size the interrupt name buffer for the full format range

[PATCH] PCI: octep: size the interrupt name buffer for the full format range

[xujiahao]

octep_hp_request_irq() formats the interrupt name with "octep_hp_%d"
into a 16-byte array.  The prefix is 9 bytes and a full-range %d
argument can add up to 11 more, so the worst case needs 21 bytes
including the terminator and 0-day reports:

  drivers/pci/hotplug/octep_hp.c:312:53: warning: '%d' directive output
  may be truncated writing between 1 and 10 bytes into a region of size 7
  [-Wformat-truncation=]
  note: 'snprintf' output between 11 and 20 bytes into a destination of
  size 16

The values passed today are OCTEP_HP_INTR_ENA and OCTEP_HP_INTR_DIS, so
no truncation actually happens, but the buffer carries no margin over
the format's worst case.  Give it the room so the warning stops coming
back from builds that cannot narrow the argument.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507261457.SXXHOjUk-lkp@intel.com/
Signed-off-by: xujiahao <xujiahao@cmss.chinamobile.com>
---
 drivers/pci/hotplug/octep_hp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/hotplug/octep_hp.c b/drivers/pci/hotplug/octep_hp.c
index a0a7f9ccb..801c080e6 100644
--- a/drivers/pci/hotplug/octep_hp.c
+++ b/drivers/pci/hotplug/octep_hp.c
@@ -52,7 +52,7 @@ struct octep_hp_slot {
 struct octep_hp_intr_info {
 	enum octep_hp_intr_type type;
 	int number;
-	char name[16];
+	char name[24];
 };
 
 struct octep_hp_controller {
-- 
2.43.0

Re: [PATCH] PCI: octep: size the interrupt name buffer for the full format range

[Bjorn Helgaas]

On Thu, Nov 05, 2026 at 05:27:04PM +0800, xujiahao wrote:
> octep_hp_request_irq() formats the interrupt name with "octep_hp_%d"
> into a 16-byte array.  The prefix is 9 bytes and a full-range %d
> argument can add up to 11 more, so the worst case needs 21 bytes
> including the terminator and 0-day reports:
> 
>   drivers/pci/hotplug/octep_hp.c:312:53: warning: '%d' directive output
>   may be truncated writing between 1 and 10 bytes into a region of size 7
>   [-Wformat-truncation=]
>   note: 'snprintf' output between 11 and 20 bytes into a destination of
>   size 16

Thanks for including the warning text.  To make the git log more
searchable, please keep the lines intact even though they are pretty
long.

Also run "git log --oneline drivers/pci/hotplug/" and match the
capitalization style.

> The values passed today are OCTEP_HP_INTR_ENA and OCTEP_HP_INTR_DIS, so

OCTEP_HP_INTR_ENA (0) and OCTEP_HP_INTR_DIS (1)

> no truncation actually happens, but the buffer carries no margin over
> the format's worst case.  Give it the room so the warning stops coming
> back from builds that cannot narrow the argument.