2020-05-12 15:23:42

by Alexander Gordeev

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

Commit 2d626158 ("lib: rework bitmap_parse()") does
not take into account order of halfwords on 64-bit
big endian architectures.

Cc: Yury Norov <[email protected]>
Signed-off-by: Alexander Gordeev <[email protected]>
---
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

2020-05-12 16:00:47

by Christian Borntraeger

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

On 12.05.20 17:21, Alexander Gordeev wrote:
> Commit 2d626158 ("lib: rework bitmap_parse()") does
> not take into account order of halfwords on 64-bit
> big endian architectures.

Karsten reported that this broke receive packet steering in 5.5 and later.
So we should add cc stable and a Fixes tag.
>
> Cc: Yury Norov <[email protected]>
> Signed-off-by: Alexander Gordeev <[email protected]>
> ---
> 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;
>