Re: [PATCH] gpib: agilent_82357a: fix null-ptr-deref in primary_address

[Dave Penkler]

On Tue, Sep 08, 2026 at 12:57:35PM -0700, Giorgi Kobakhia wrote:
> The function agilent_82357a_primary_address initializes usb_dev with
> interface_to_usbdev(a_priv->bus_interface) above the guarding if
> (!a_priv->bus_interface) return -ENODEV; When the usb dongle is
> unplugged, disconnect() sets bus_interface to NULL and the NULL
> dereference is triggered.
> 
> Commit 8491e73a5223 ("staging: gpib: Fix Oops after disconnect in
> agilent usb") fixes multiple NULL dereferences in other functions,
> but this one is left out.
> 
> KASAN report for the left-out NULL deref:
>  Oops: general protection fault, probably for non-canonical address ...
>  KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
>  RIP: 0010:agilent_82357a_primary_address (./include/linux/usb.h:752
>   drivers/gpib/agilent_82357a/agilent_82357a.c:922)
>  Call Trace:
>   ibpad (drivers/gpib/common/iblib.c:466)
>   ibioctl (drivers/gpib/common/gpib_os.c:1507
>   drivers/gpib/common/gpib_os.c:675) __x64_sys_ioctl (fs/ioctl.c:51
>   fs/ioctl.c:597 fs/ioctl.c:583 fs/ioctl.c:583) do_syscall_64
>   (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84)
>   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
>  Kernel panic - not syncing: Fatal exception
> 
> Remove the faulty assignment.
> 
> Fixes: fbae7090f30c ("staging: gpib: Update messaging and usb_device refs in agilent_usb")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Giorgi Kobakhia <gkobakhi@xxxxxxxx>

Acked-by: Dave Penkler <dpenkler@xxxxxxxxx>
> ---
>  drivers/gpib/agilent_82357a/agilent_82357a.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpib/agilent_82357a/agilent_82357a.c b/drivers/gpib/agilent_82357a/agilent_82357a.c
> index 2468a471d175..7abe5540ffc5 100644
> --- a/drivers/gpib/agilent_82357a/agilent_82357a.c
> +++ b/drivers/gpib/agilent_82357a/agilent_82357a.c
> @@ -919,7 +919,7 @@ static unsigned int agilent_82357a_update_status(struct gpib_board *board,
>  static int agilent_82357a_primary_address(struct gpib_board *board, unsigned int address)
>  {
>  	struct agilent_82357a_priv *a_priv = board->private_data;
> -	struct usb_device *usb_dev = interface_to_usbdev(a_priv->bus_interface);
> +	struct usb_device *usb_dev;
>  	struct agilent_82357a_register_pairlet write;
>  	int retval;
>  
> -- 
> 2.43.0
>