is_power_of_2(size) will be failed if size is 0, and then it calls
roundup_pow_of_two(0), then will return a quite *huge* value(well, the
comments at roundup_pow_of_two macro says: the result is undefined when
n == 0).
Moving the size check before power of 2 testing and rounding will fix
this "not really happened yet" issue.
Cc: Stefani Seibold <stef...@seibold.net>
Cc: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Yuanhan Liu <yuanhan....@linux.intel.com>
---
kernel/kfifo.c | 22 ++++++++++------------
1 files changed, 10 insertions(+), 12 deletions(-)
diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index 0f78378..e3a63c6 100644
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -38,13 +38,6 @@ static inline unsigned int kfifo_unused(struct __kfifo *fifo)
int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
size_t esize, gfp_t gfp_mask)
{
- /*
- * round up to the next power of 2, since our 'let the indices
- * wrap' technique works only in this case.
- */
- if (!is_power_of_2(size))
- size = roundup_pow_of_two(size);
-
fifo->in = 0;
fifo->out = 0;
fifo->esize = esize;
@@ -54,6 +47,12 @@ int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
fifo->mask = 0;
return -EINVAL;
}
+ /*
+ * round up to the next power of 2, since our 'let the indices
+ * wrap' technique works only in this case.
+ */
+ if (!is_power_of_2(size))
+ size = roundup_pow_of_two(size);
fifo->data = kmalloc(size * esize, gfp_mask);
@@ -81,20 +80,19 @@ EXPORT_SYMBOL(__kfifo_free);
int __kfifo_init(struct __kfifo *fifo, void *buffer,
unsigned int size, size_t esize)
{
- size /= esize;
-
- if (!is_power_of_2(size))
- size = roundup_pow_of_two(size);
-
fifo->in = 0;
fifo->out = 0;
fifo->esize = esize;
fifo->data = buffer;
+ size /= esize;
if (size < 2) {
fifo->mask = 0;
return -EINVAL;
}
+ if (!is_power_of_2(size))
+ size = roundup_pow_of_two(size);
+
fifo->mask = size - 1;
return 0;
--
1.7.7.6
--
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