diff options
| author | Jacob Garber <jgarber1@ualberta.ca> | 2019-08-09 17:13:59 -0600 |
|---|---|---|
| committer | Anup Patel <anup.patel@wdc.com> | 2019-08-12 09:26:38 +0530 |
| commit | 5e4021a2f5ca346d1c12b80d346c1a2e7eb4b501 (patch) | |
| tree | f30705dc9c46ec8c2e58573f3542ad53f84a77ba /lib/sbi/sbi_fifo.c | |
| parent | 6ddf71e6e90878ee107b0d9f98492ad27d31c73a (diff) | |
lib: Prevent unintended sign extensions
In the last argument to sbi_memset() we essentially have the following
multiplication:
size_t = u16 * u16
Due to C's integer semantics, both u16's are implicitly converted to int
before the multiplication, which cannot hold all possible values of a
u16 * u16. If the multiplication overflows, the intermediate result will
be a negative number. On 64-bit platforms, this will be sign-extended to
a huge integer in the conversion to a u64 (aka size_t). Being the size
argument to sbi_memset(), this could potentially cause a large
out-of-bounds write. The solution is to manually cast one of the u16 to
a size_t, which will make it large enough to avoid the implicit
conversion and any overflow.
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Diffstat (limited to 'lib/sbi/sbi_fifo.c')
| -rw-r--r-- | lib/sbi/sbi_fifo.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/lib/sbi/sbi_fifo.c b/lib/sbi/sbi_fifo.c index e69009f..18ff0d6 100644 --- a/lib/sbi/sbi_fifo.c +++ b/lib/sbi/sbi_fifo.c @@ -20,7 +20,7 @@ void sbi_fifo_init(struct sbi_fifo *fifo, void *queue_mem, u16 entries, fifo->entry_size = entry_size; SPIN_LOCK_INIT(&fifo->qlock); fifo->avail = fifo->tail = 0; - sbi_memset(fifo->queue, 0, entries * entry_size); + sbi_memset(fifo->queue, 0, (size_t)entries * entry_size); } /* Note: must be called with fifo->qlock held */ @@ -74,9 +74,11 @@ bool sbi_fifo_is_empty(struct sbi_fifo *fifo) /* Note: must be called with fifo->qlock held */ static inline void __sbi_fifo_reset(struct sbi_fifo *fifo) { + size_t size = (size_t)fifo->num_entries * fifo->entry_size; + fifo->avail = 0; fifo->tail = 0; - sbi_memset(fifo->queue, 0, fifo->num_entries * fifo->entry_size); + sbi_memset(fifo->queue, 0, size); } bool sbi_fifo_reset(struct sbi_fifo *fifo) |