The patch titled
Subject: lib/test_bitmap.c: do not accidentally use stack VLA
has been added to the -mm tree. Its filename is
test_bitmap-do-not-accidentally-use-stack-vla.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/test_bitmap-do-not-accidentally-use-stack-vla.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/test_bitmap-do-not-accidentally-use-stack-vla.patch
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------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: lib/test_bitmap.c: do not accidentally use stack VLA
This avoids an accidental stack VLA (since the compiler thinks the value
of "len" can change, even when marked "const"). This just replaces it
with a #define so it will DTRT.
Seen with -Wvla. Fixed as part of the directive to remove all VLAs from
the kernel: https://lkml.org/lkml/2018/3/7/621
Link: http://lkml.kernel.org/r/20180307212555.GA17927@beast
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/test_bitmap.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN lib/test_bitmap.c~test_bitmap-do-not-accidentally-use-stack-vla lib/test_bitmap.c
--- a/lib/test_bitmap.c~test_bitmap-do-not-accidentally-use-stack-vla
+++ a/lib/test_bitmap.c
@@ -292,15 +292,17 @@ static void __init test_bitmap_parselist
}
}
+#define EXP_BYTES (sizeof(exp) * 8)
+
static void __init test_bitmap_arr32(void)
{
- unsigned int nbits, next_bit, len = sizeof(exp) * 8;
+ unsigned int nbits, next_bit;
u32 arr[sizeof(exp) / 4];
- DECLARE_BITMAP(bmap2, len);
+ DECLARE_BITMAP(bmap2, EXP_BYTES);
memset(arr, 0xa5, sizeof(arr));
- for (nbits = 0; nbits < len; ++nbits) {
+ for (nbits = 0; nbits < EXP_BYTES; ++nbits) {
bitmap_to_arr32(arr, exp, nbits);
bitmap_from_arr32(bmap2, arr, nbits);
expect_eq_bitmap(bmap2, exp, nbits);
@@ -312,7 +314,7 @@ static void __init test_bitmap_arr32(voi
" tail is not safely cleared: %d\n",
nbits, next_bit);
- if (nbits < len - 32)
+ if (nbits < EXP_BYTES - 32)
expect_eq_uint(arr[DIV_ROUND_UP(nbits, 32)],
0xa5a5a5a5);
}
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
bug-use-%pb-in-bug-and-stack-protector-failure.patch
bug-exclude-non-bug-warn-exceptions-from-report_bug.patch
taint-convert-to-indexed-initialization.patch
taint-consolidate-documentation.patch
taint-add-taint-for-randstruct.patch
test_bitmap-do-not-accidentally-use-stack-vla.patch
fork-unconditionally-clear-stack-on-fork.patch
exec-pass-stack-rlimit-into-mm-layout-functions.patch
exec-introduce-finalize_exec-before-start_thread.patch
exec-pin-stack-limit-during-exec.patch
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