5.15-stable review patch. If anyone has any objections, please let me know.
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From: Dave Penkler dpenkler@gmail.com
commit acb3dac2805d3342ded7dbbd164add32bbfdf21c upstream.
The usbtmc488_ioctl_read_stb function relied on a positive return from usbtmc_get_stb to reset the srq condition in the driver. The USBTMC_IOCTL_GET_STB case tested for a positive return to return the stb to the user.
Commit: <cac01bd178d6> ("usb: usbtmc: Fix erroneous get_stb ioctl error returns") changed the return value of usbtmc_get_stb to 0 on success instead of returning the value of usb_control_msg which is positive in the normal case. This change caused the function usbtmc488_ioctl_read_stb and the USBTMC_IOCTL_GET_STB ioctl to no longer function correctly.
Change the test in usbtmc488_ioctl_read_stb to test for failure first and return the failure code immediately. Change the test for the USBTMC_IOCTL_GET_STB ioctl to test for 0 instead of a positive value.
Fixes: cac01bd178d6 ("usb: usbtmc: Fix erroneous get_stb ioctl error returns") Cc: stable@vger.kernel.org Signed-off-by: Dave Penkler dpenkler@gmail.com Link: https://lore.kernel.org/r/20250521121656.18174-3-dpenkler@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/class/usbtmc.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
--- a/drivers/usb/class/usbtmc.c +++ b/drivers/usb/class/usbtmc.c @@ -565,14 +565,15 @@ static int usbtmc488_ioctl_read_stb(stru
rv = usbtmc_get_stb(file_data, &stb);
- if (rv > 0) { - srq_asserted = atomic_xchg(&file_data->srq_asserted, - srq_asserted); - if (srq_asserted) - stb |= 0x40; /* Set RQS bit */ + if (rv < 0) + return rv; + + srq_asserted = atomic_xchg(&file_data->srq_asserted, srq_asserted); + if (srq_asserted) + stb |= 0x40; /* Set RQS bit */ + + rv = put_user(stb, (__u8 __user *)arg);
- rv = put_user(stb, (__u8 __user *)arg); - } return rv;
} @@ -2201,7 +2202,7 @@ static long usbtmc_ioctl(struct file *fi
case USBTMC_IOCTL_GET_STB: retval = usbtmc_get_stb(file_data, &tmp_byte); - if (retval > 0) + if (!retval) retval = put_user(tmp_byte, (__u8 __user *)arg); break;