According to the documentation of fcntl, some commands take an int as argument. In practice not all of them enforce this behaviour, as they instead accept a more permissive long and in most cases not even a range check is performed.
An issue could possibly arise from a combination of the handling of the varargs in user space and the ABI rules of the target, which may result in the top bits of an int argument being non-zero.
This issue was originally raised and detailed in the following thread: https://lore.kernel.org/linux-api/Y1%2FDS6uoWP7OSkmd@arm.com/ And was discovered during the porting of Linux to Morello [1].
This series modifies the interested commands so that they explicitly take an int argument. It also propagates this change down to helper and related functions as necessary.
This series is also available on my fork at: https://git.morello-project.org/Sevenarth/linux/-/commits/fcntl-int-handling...
Best regards, Luca Vizzarro
[1] https://git.morello-project.org/morello/kernel/linux
Luca Vizzarro (5): fcntl: Cast commands with int args explicitly fs: Pass argument to fcntl_setlease as int pipe: Pass argument of pipe_fcntl as int memfd: Pass argument of memfd_fcntl as int dnotify: Pass argument of fcntl_dirnotify as int
fs/cifs/cifsfs.c | 2 +- fs/fcntl.c | 29 +++++++++++++++-------------- fs/libfs.c | 2 +- fs/locks.c | 20 ++++++++++---------- fs/nfs/nfs4_fs.h | 2 +- fs/nfs/nfs4file.c | 2 +- fs/nfs/nfs4proc.c | 4 ++-- fs/notify/dnotify/dnotify.c | 4 ++-- fs/pipe.c | 6 +++--- include/linux/dnotify.h | 4 ++-- include/linux/filelock.h | 12 ++++++------ include/linux/fs.h | 6 +++--- include/linux/memfd.h | 4 ++-- include/linux/pipe_fs_i.h | 4 ++-- mm/memfd.c | 6 +----- 15 files changed, 52 insertions(+), 55 deletions(-)