[PATCH RESEND] lib: fix bitmap_parse() on 64-bit big endian archs

Alexander Gordeev
2020-05-18T10:34:50Z

Commit 2d6261583be0 ("lib: rework bitmap_parse()") does
not take into account order of halfwords on 64-bit big
endian architectures.

Fixes: 2d6261583be0 ("lib: rework bitmap_parse()")
Cc: stable@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Amritha Nambiar <amritha.nambiar@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: "Tobin C . Harding" <tobin@kernel.org>
Cc: Vineet Gupta <vineet.gupta1@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
lib/bitmap.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 89260aa..a725e46 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -717,6 +717,19 @@ static const char *bitmap_get_x32_reverse(const char *start,
return end;
}

+#if defined(__BIG_ENDIAN) && defined(CONFIG_64BIT)
+static void save_x32_chunk(unsigned long *maskp, u32 chunk, int chunk_idx)
+{
+ maskp += (chunk_idx / 2);
+ ((u32 *)maskp)[(chunk_idx & 1) ^ 1] = chunk;
+}
+#else
+static void save_x32_chunk(unsigned long *maskp, u32 chunk, int chunk_idx)
+{
+ ((u32 *)maskp)[chunk_idx] = chunk;
+}
+#endif
+
/**
* bitmap_parse - convert an ASCII hex string into a bitmap.
* @start: pointer to buffer containing string.
@@ -738,7 +751,8 @@ int bitmap_parse(const char *start, unsigned int buflen,
{
const char *end = strnchrnul(start, buflen, '\n') - 1;
int chunks = BITS_TO_U32(nmaskbits);
- u32 *bitmap = (u32 *)maskp;
+ int chunk_idx = 0;
+ u32 chunk;
int unset_bit;

while (1) {
@@ -749,9 +763,11 @@ int bitmap_parse(const char *start, unsigned int buflen,
if (!chunks--)
return -EOVERFLOW;

- end = bitmap_get_x32_reverse(start, end, bitmap++);
+ end = bitmap_get_x32_reverse(start, end, &chunk);
if (IS_ERR(end))
return PTR_ERR(end);
+
+ save_x32_chunk(maskp, chunk, chunk_idx++);
}

unset_bit = (BITS_TO_U32(nmaskbits) - chunks) * 32;
--
1.8.3.1