On Fri, Oct 17, 2025 at 02:43:14PM +0200, Jan Kara wrote:
On Fri 17-10-25 11:40:41, Cyril Hrubis wrote:
Hi!
## Test error log tst_buffers.c:57: TINFO: Test is using guarded buffers tst_test.c:2021: TINFO: LTP version: 20250930 tst_test.c:2024: TINFO: Tested kernel: 6.18.0-rc1 #1 SMP PREEMPT @1760657272 aarch64 tst_kconfig.c:88: TINFO: Parsing kernel config '/proc/config.gz' tst_kconfig.c:676: TINFO: CONFIG_TRACE_IRQFLAGS kernel option detected which might slow the execution tst_test.c:1842: TINFO: Overall timeout per run is 0h 21m 36s ioctl_pidfd05.c:45: TPASS: ioctl(pidfd, PIDFD_GET_INFO, NULL) : EINVAL (22) ioctl_pidfd05.c:46: TFAIL: ioctl(pidfd, PIDFD_GET_INFO_SHORT, info_invalid) expected EINVAL: ENOTTY (25)
Looking closely this is a different problem.
What we do in the test is that we pass PIDFD_IOCTL_INFO whith invalid size with:
struct pidfd_info_invalid { uint32_t dummy; };
#define PIDFD_GET_INFO_SHORT _IOWR(PIDFS_IOCTL_MAGIC, 11, struct pidfd_info_invalid)
And we expect to hit:
if (usize < PIDFD_INFO_SIZE_VER0) return -EINVAL; /* First version, no smaller struct possible */
in fs/pidfs.c
And apparently the return value was changed in:
commit 3c17001b21b9f168c957ced9384abe969019b609 Author: Christian Brauner brauner@kernel.org Date: Fri Sep 12 13:52:24 2025 +0200
pidfs: validate extensible ioctls
Validate extensible ioctls stricter than we do now. Reviewed-by: Aleksa Sarai cyphar@cyphar.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Christian Brauner brauner@kernel.org
diff --git a/fs/pidfs.c b/fs/pidfs.c index edc35522d75c..0a5083b9cce5 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -440,7 +440,7 @@ static bool pidfs_ioctl_valid(unsigned int cmd) * erronously mistook the file descriptor for a pidfd. * This is not perfect but will catch most cases. */
return (_IOC_TYPE(cmd) == _IOC_TYPE(PIDFD_GET_INFO));
return extensible_ioctl_valid(cmd, PIDFD_GET_INFO, PIDFD_INFO_SIZE_VER0); }
return false;
So kernel has changed error it returns, if this is a regression or not is for kernel developers to decide.
Yes, it's mostly a question to Christian whether if passed size for extensible ioctl is smaller than minimal, we should be returning ENOIOCTLCMD or EINVAL. I think EINVAL would make more sense but Christian is our "extensible ioctl expert" :).
You're asking difficult questions actually. :D I think it would be completely fine to return EINVAL in this case. But traditionally ENOTTY has been taken to mean that this is not a supported ioctl. This translation is done by the VFS layer itself iirc.