6.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
[ Upstream commit 29b95ac917927ce9f95bf38797e16333ecb489b1 ]
With *ENTER_EXT_ARG_REG instead of passing a user pointer with arguments
for the waiting loop the user can specify an offset into a pre-mapped
region of memory, in which case the
[offset, offset + sizeof(io_uring_reg_wait)) will be intepreted as the
argument.
As we address a kernel array using a user given index, it'd be a subject
to speculation type of exploits. Use array_index_nospec() to prevent
that. Make sure to pass not the full region size but truncate by the
maximum offset allowed considering the structure size.
Fixes: d617b3147d54c ("io_uring: restore back registered wait arguments")
Fixes: aa00f67adc2c0 ("io_uring: add support for fixed wait regions")
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/1e3d9da7c43d619de7bcf41d1cd277ab2688c443.1733694126.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
io_uring/io_uring.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 4758f1ba902b9..d062c5c69211b 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3233,6 +3233,7 @@ static struct io_uring_reg_wait *io_get_ext_arg_reg(struct io_ring_ctx *ctx,
end > ctx->cq_wait_size))
return ERR_PTR(-EFAULT);
+ offset = array_index_nospec(offset, ctx->cq_wait_size - size);
return ctx->cq_wait_arg + offset;
}
--
2.39.5
