The patch titled
Subject: mm, kasan: proper instrument _kernel_nofault
has been added to the -mm mm-unstable branch. Its filename is
mm-instrument-copy_from-to_kernel_nofault-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-instrument-copy_from-to_kernel_nofault-fix.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@xxxxxxxxx>
Subject: mm, kasan: proper instrument _kernel_nofault
Date: Mon, 30 Sep 2024 15:24:05 +0500
In commit 88ad9dc30bbf("mm, kasan: instrument
copy_from/to_kernel_nofault"), both src and dst were checked which might
lead to the false-positive reports.
Regular instrument_read() for copy_from and instrument_write() for copy_to
triggers KASAN reports in mm/kasan_test_c.c
copy_from_to_kernel_nofault_oob() kunit test.
Tested on x86_64, arm64 with CONFIG_KASAN_SW_TAGS using the latest
linux-next tree, where this commit has been merged today.
Link: https://lkml.kernel.org/r/20240930102405.2227124-1-snovitoll@xxxxxxxxx
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@xxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=210505
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/maccess.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/mm/maccess.c~mm-instrument-copy_from-to_kernel_nofault-fix
+++ a/mm/maccess.c
@@ -32,7 +32,7 @@ long copy_from_kernel_nofault(void *dst,
return -ERANGE;
pagefault_disable();
- instrument_memcpy_before(dst, src, size);
+ instrument_read(src, size);
if (!(align & 7))
copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
if (!(align & 3))
@@ -40,7 +40,6 @@ long copy_from_kernel_nofault(void *dst,
if (!(align & 1))
copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
- instrument_memcpy_after(dst, src, size, 0);
pagefault_enable();
return 0;
Efault:
@@ -65,7 +64,7 @@ long copy_to_kernel_nofault(void *dst, c
align = (unsigned long)dst | (unsigned long)src;
pagefault_disable();
- instrument_memcpy_before(dst, src, size);
+ instrument_write(dst, size);
if (!(align & 7))
copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
if (!(align & 3))
@@ -73,7 +72,6 @@ long copy_to_kernel_nofault(void *dst, c
if (!(align & 1))
copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
- instrument_memcpy_after(dst, src, size, 0);
pagefault_enable();
return 0;
Efault:
_
Patches currently in -mm which might be from snovitoll@xxxxxxxxx are
mm-instrument-copy_from-to_kernel_nofault.patch
mm-instrument-copy_from-to_kernel_nofault-fix.patch
