From: Pavel Begunkov asml.silence@gmail.com

stable inclusion from stable-v5.10.36 commit cbbc13b115b8f18e0a714d89f87fbdc499acfe2d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I94JIH CVE: CVE-2021-47040

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=t...

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[ Upstream commit 38134ada0ceea3e848fe993263c0ff6207fd46e7 ]

Colin reported before possible overflow and sign extension problems in io_provide_buffers_prep(). As Linus pointed out previous attempt did nothing useful, see d81269fecb8ce ("io_uring: fix provide_buffers sign extension").

Do that with help of check_<op>_overflow helpers. And fix struct io_provide_buf::len type, as it doesn't make much sense to keep it signed.

Reported-by: Colin Ian King colin.king@canonical.com Fixes: efe68c1ca8f49 ("io_uring: validate the full range of provided buffers for access") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/46538827e70fce5f6cdb50897cff4cacc490f380.161848825... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Long Li leo.lilong@huawei.com --- fs/io_uring.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c index 018d38bec473..afac3197fd6c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -486,7 +486,7 @@ struct io_splice { struct io_provide_buf { struct file *file; __u64 addr; - __s32 len; + __u32 len; __u32 bgid; __u16 nbufs; __u16 bid; @@ -3606,7 +3606,7 @@ static int io_remove_buffers(struct io_kiocb *req, bool force_nonblock, static int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) { - unsigned long size; + unsigned long size, tmp_check; struct io_provide_buf *p = &req->pbuf; u64 tmp;

@@ -3620,6 +3620,12 @@ static int io_provide_buffers_prep(struct io_kiocb *req, p->addr = READ_ONCE(sqe->addr); p->len = READ_ONCE(sqe->len);

+ if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs, + &size)) + return -EOVERFLOW; + if (check_add_overflow((unsigned long)p->addr, size, &tmp_check)) + return -EOVERFLOW; + size = (unsigned long)p->len * p->nbufs; if (!access_ok(u64_to_user_ptr(p->addr), size)) return -EFAULT;