Re: [PATCH] s390/3270: return -ENOTTY for unknown ioctls in fs3270_ioctl()

[sashiko-bot@kernel.org]

> fs3270_ioctl() initializes rc to 0 and its cmd switch has no default
> branch, so an unrecognized ioctl command returns success without doing
> anything. Follow the ioctl convention and reject unknown commands with
> -ENOTTY.
> 
> Verified against Linux 7.3-rc6 (a90ee4305c4a5df72c11b31dacfdc76e00fcf78a),
> the current mainline master: rc is initialised to 0, the switch covers
> TUBICMD, TUBOCMD, TUBGETI, TUBGETO and TUBGETMOD only and has no default
> branch, so an unknown command returns success without doing anything. The
> file is byte-identical between 7.3-rc5 and 7.3-rc6.
> 
> Sibling audit (same snapshot, all NOT bugs -- do not re-report):
> - drivers/s390/char/keyboard.c:kbd_ioctl HAS default -> -ENOIOCTLCMD;
>   do_kdsk/do_kdgkb lack default but only reachable via whitelisted
>   cmds from kbd_ioctl, harmless.
> - drivers/char/nvram.c:nvram_misc_ioctl inits ret=-ENOTTY, safe.
> - drivers/misc/tps6594-pfsm.c inits ret=-ENOIOCTLCMD, safe.
> - drivers/misc/pci_endpoint_test.c inits ret=-EINVAL, safe (error).
> Only fs3270 inits 0 -> true positive.
> 
> Signed-off-by: Shirong Zhao <shxzhaosr@163.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261005055825.20-1-shxzhaosr@163.com?part=1