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io_uring: fix provide_buffers sign extension

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io_provide_buffers_prep()'s "p->len * p->nbufs" to sign extension
problems. Not a huge problem as it's only used for access_ok() and
increases the checked length, but better to keep typing right.

Reported-by: Colin Ian King <colin.king@canonical.com>
Fixes: efe68c1ca8 ("io_uring: validate the full range of provided buffers for access")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/562376a39509e260d8532186a06226e56eb1f594.1616149233.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-03-19 10:21:19 +00:00 committed by Jens Axboe
parent b65c128f96
commit d81269fecb
1 changed files with 3 additions and 1 deletions
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4
fs/io_uring.c
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@ -3977,6 +3977,7 @@ static int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
static int io_provide_buffers_prep(struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
unsigned long size;
struct io_provide_buf *p = &req->pbuf;
u64 tmp;
@ -3990,7 +3991,8 @@ static int io_provide_buffers_prep(struct io_kiocb *req,
p->addr = READ_ONCE(sqe->addr);
p->len = READ_ONCE(sqe->len);
if (!access_ok(u64_to_user_ptr(p->addr), (p->len * p->nbufs)))
size = (unsigned long)p->len * p->nbufs;
if (!access_ok(u64_to_user_ptr(p->addr), size))
return -EFAULT;
p->bgid = READ_ONCE(sqe->buf_group);