+ mm-kasan-kmsan-copy_from-to_kernel_nofault-v3.patch added to mm-unstable branch

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

The patch titled
     Subject: mm-kasan-kmsan-copy_from-to_kernel_nofault-v3
has been added to the -mm mm-unstable branch.  Its filename is
     mm-kasan-kmsan-copy_from-to_kernel_nofault-v3.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kasan-kmsan-copy_from-to_kernel_nofault-v3.patch

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

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------------------------------------------------------
From: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Subject: mm-kasan-kmsan-copy_from-to_kernel_nofault-v3
Date: Tue, 8 Oct 2024 15:15:26 +0500

v2:
- squashed previous submitted in -mm tree 2 patches based on Linus tree
v3:
- moved checks to *_nofault_loop macros per Marco's comments
- edited the commit message

Link: https://lore.kernel.org/linux-mm/CANpmjNMAVFzqnCZhEity9cjiqQ9CVN1X7qeeeAp_6yKjwKo8iw@mail.gmail.com/
Link: https://lkml.kernel.org/r/20241008101526.2591147-1-snovitoll@gmail.com
Suggested-by: Marco Elver <elver@google.com>
Reported-by: syzbot+61123a5daeb9f7454599@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=61123a5daeb9f7454599
Reported-by: Andrey Konovalov <andreyknvl@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=210505
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/maccess.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/mm/maccess.c~mm-kasan-kmsan-copy_from-to_kernel_nofault-v3
+++ a/mm/maccess.c
@@ -13,9 +13,14 @@ bool __weak copy_from_kernel_nofault_all
 	return true;
 }
 
+/*
+ * The below only uses kmsan_check_memory() to ensure uninitialized kernel
+ * memory isn't leaked.
+ */
 #define copy_from_kernel_nofault_loop(dst, src, len, type, err_label)	\
 	while (len >= sizeof(type)) {					\
 		__get_kernel_nofault(dst, src, type, err_label);	\
+		kmsan_check_memory(src, sizeof(type));			\
 		dst += sizeof(type);					\
 		src += sizeof(type);					\
 		len -= sizeof(type);					\
@@ -31,8 +36,6 @@ long copy_from_kernel_nofault(void *dst,
 	if (!copy_from_kernel_nofault_allowed(src, size))
 		return -ERANGE;
 
-	/* Make sure uninitialized kernel memory isn't copied. */
-	kmsan_check_memory(src, size);
 	pagefault_disable();
 	if (!(align & 7))
 		copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
@@ -52,6 +55,7 @@ EXPORT_SYMBOL_GPL(copy_from_kernel_nofau
 #define copy_to_kernel_nofault_loop(dst, src, len, type, err_label)	\
 	while (len >= sizeof(type)) {					\
 		__put_kernel_nofault(dst, src, type, err_label);	\
+		instrument_write(dst, sizeof(type));			\
 		dst += sizeof(type);					\
 		src += sizeof(type);					\
 		len -= sizeof(type);					\
@@ -64,7 +68,6 @@ long copy_to_kernel_nofault(void *dst, c
 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
 		align = (unsigned long)dst | (unsigned long)src;
 
-	instrument_write(dst, size);
 	pagefault_disable();
 	if (!(align & 7))
 		copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
_

Patches currently in -mm which might be from snovitoll@gmail.com are

mm-kasan-kmsan-copy_from-to_kernel_nofault.patch
mm-kasan-kmsan-copy_from-to_kernel_nofault-v3.patch