+ kmsan-enter-the-runtime-around-kmsan_internal_memmove_metadata-call.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: kmsan: enter the runtime around kmsan_internal_memmove_metadata() call
has been added to the -mm mm-new branch.  Its filename is
     kmsan-enter-the-runtime-around-kmsan_internal_memmove_metadata-call.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kmsan-enter-the-runtime-around-kmsan_internal_memmove_metadata-call.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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fixup patches in mm-new.

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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------------------------------------------------------
From: Alexander Potapenko <glider@google.com>
Subject: kmsan: enter the runtime around kmsan_internal_memmove_metadata() call
Date: Wed, 7 May 2025 18:00:11 +0200

kmsan_internal_memmove_metadata() transitively calls stack_depot_save()
(via kmsan_internal_chain_origin() and kmsan_save_stack_with_flags()),
which may allocate memory.  Guard it with kmsan_enter_runtime() and
kmsan_leave_runtime() to avoid recursion.

This bug was spotted by CONFIG_WARN_CAPABILITY_ANALYSIS=y

Link: https://lkml.kernel.org/r/20250507160012.3311104-4-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kmsan/hooks.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/kmsan/hooks.c~kmsan-enter-the-runtime-around-kmsan_internal_memmove_metadata-call
+++ a/mm/kmsan/hooks.c
@@ -275,8 +275,10 @@ void kmsan_copy_to_user(void __user *to,
 		 * Don't check anything, just copy the shadow of the copied
 		 * bytes.
 		 */
+		kmsan_enter_runtime();
 		kmsan_internal_memmove_metadata((void *)to, (void *)from,
 						to_copy - left);
+		kmsan_leave_runtime();
 	}
 	user_access_restore(ua_flags);
 }
_

Patches currently in -mm which might be from glider@google.com are

kmsan-apply-clang-format-to-files-mm-kmsan.patch
kmsan-fix-usage-of-kmsan_enter_runtime-in-kmsan_vmap_pages_range_noflush.patch
kmsan-drop-the-declaration-of-kmsan_save_stack.patch
kmsan-enter-the-runtime-around-kmsan_internal_memmove_metadata-call.patch
kmsan-rework-kmsan_in_runtime-handling-in-kmsan_report.patch