* [PATCH] io_uring: protect fixed file indexing with array_index_nospec()
@ 2019-10-26 13:51 Jens Axboe
0 siblings, 0 replies; only message in thread
From: Jens Axboe @ 2019-10-26 13:51 UTC (permalink / raw)
To: linux-block@vger.kernel.org; +Cc: Jann Horn
We index the file tables with a user given value. After we check
it's within our limits, use array_index_nospec() to prevent any
spectre attacks here.
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4402485f0879..769a8c7eee37 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2320,6 +2320,7 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
if (unlikely(!ctx->user_files ||
(unsigned) fd >= ctx->nr_user_files))
return -EBADF;
+ fd = array_index_nospec(fd, ctx->nr_user_files);
if (!ctx->user_files[fd])
return -EBADF;
req->file = ctx->user_files[fd];
--
Jens Axboe
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2019-10-26 13:51 [PATCH] io_uring: protect fixed file indexing with array_index_nospec() Jens Axboe
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