Commit 7ea24326 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring/query: cap number of queries 



If a query chain forms a cycle, it'll be looping in the kernel until the
process is killed. It might be fine as any such mistake can be easily
uncovered during testing, but it's still nicer to let it break out of
the syscall if it executed too many queries.

Suggested-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2408d178

io_uring/query.c

+5 −1
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include "io_uring.h"



#define IO_MAX_QUERY_SIZE		(sizeof(struct io_uring_query_opcode))

#define IO_MAX_QUERY_ENTRIES		1000



static ssize_t io_query_ops(void *data)

{
@@ -74,7 +75,7 @@ int io_query(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args) 
{

	char entry_buffer[IO_MAX_QUERY_SIZE];

	void __user *uhdr = arg;

	int ret;

	int ret, nr = 0;



	memset(entry_buffer, 0, sizeof(entry_buffer));
@@ -89,6 +90,9 @@ int io_query(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args) 
			return ret;

		uhdr = u64_to_user_ptr(next_hdr);



		/* Have some limit to avoid a potential cycle */

		if (++nr >= IO_MAX_QUERY_ENTRIES)

			return -ERANGE;

		if (fatal_signal_pending(current))

			return -EINTR;

		cond_resched();