From 0f20bba1688bdf3b32df0162511a67d4eda15790 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Tue, 3 Oct 2023 00:14:52 +0100 Subject: mm/gup: explicitly define and check internal GUP flags, disallow FOLL_TOUCH Rather than open-coding a list of internal GUP flags in is_valid_gup_args(), define which ones are internal. In addition, explicitly check to see if the user passed in FOLL_TOUCH somehow, as this appears to have been accidentally excluded. Link: https://lkml.kernel.org/r/971e013dfe20915612ea8b704e801d7aef9a66b6.1696288092.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Arnd Bergmann Reviewed-by: David Hildenbrand Reviewed-by: Jason Gunthorpe Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Catalin Marinas Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Hubbard Cc: Mark Rutland Cc: Namhyung Kim Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Richard Cochran Cc: Will Deacon Signed-off-by: Andrew Morton --- mm/gup.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'mm/gup.c') diff --git a/mm/gup.c b/mm/gup.c index 2f8a2d89fde1..b21b33d1787e 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2227,12 +2227,11 @@ static bool is_valid_gup_args(struct page **pages, int *locked, /* * These flags not allowed to be specified externally to the gup * interfaces: - * - FOLL_PIN/FOLL_TRIED/FOLL_FAST_ONLY are internal only + * - FOLL_TOUCH/FOLL_PIN/FOLL_TRIED/FOLL_FAST_ONLY are internal only * - FOLL_REMOTE is internal only and used on follow_page() * - FOLL_UNLOCKABLE is internal only and used if locked is !NULL */ - if (WARN_ON_ONCE(gup_flags & (FOLL_PIN | FOLL_TRIED | FOLL_UNLOCKABLE | - FOLL_REMOTE | FOLL_FAST_ONLY))) + if (WARN_ON_ONCE(gup_flags & INTERNAL_GUP_FLAGS)) return false; gup_flags |= to_set; -- cgit v1.2.3 From 9c4b21422507035f3e0a507a680c9b03c0bcc730 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Tue, 3 Oct 2023 00:14:53 +0100 Subject: mm/gup: make failure to pin an error if FOLL_NOWAIT not specified There really should be no circumstances under which a non-FOLL_NOWAIT GUP operation fails to return any pages, so make this an error and warn on it. To catch the trivial case, simply exit early if nr_pages == 0. This brings __get_user_pages_locked() in line with the behaviour of its nommu variant. Link: https://lkml.kernel.org/r/2a42d96dd1e37163f90a0019a541163dafb7e4c3.1696288092.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Arnd Bergmann Reviewed-by: David Hildenbrand Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Catalin Marinas Cc: Ian Rogers Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Jiri Olsa Cc: John Hubbard Cc: Mark Rutland Cc: Namhyung Kim Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Richard Cochran Cc: Will Deacon Signed-off-by: Andrew Morton --- mm/gup.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'mm/gup.c') diff --git a/mm/gup.c b/mm/gup.c index b21b33d1787e..231711efa390 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1471,6 +1471,9 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, long ret, pages_done; bool must_unlock = false; + if (!nr_pages) + return 0; + /* * The internal caller expects GUP to manage the lock internally and the * lock must be released when this returns. @@ -1595,6 +1598,14 @@ retry: mmap_read_unlock(mm); *locked = 0; } + + /* + * Failing to pin anything implies something has gone wrong (except when + * FOLL_NOWAIT is specified). + */ + if (WARN_ON_ONCE(pages_done == 0 && !(flags & FOLL_NOWAIT))) + return -EFAULT; + return pages_done; } -- cgit v1.2.3