diff options
| author | Tom Ryan <ryan36005@gmail.com> | 2026-03-09 22:20:02 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-03-11 14:35:19 -0600 |
| commit | 6f02c6b196036dbb6defb4647d8707d29b7fe95b (patch) | |
| tree | 0758a3cd563b45231e2484e8b294dd11218396b2 | |
| parent | 177c69432161f6e4bab07ccacf8a1748a6898a6b (diff) | |
io_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops
When IORING_SETUP_SQE_MIXED is used without IORING_SETUP_NO_SQARRAY,
the boundary check for 128-byte SQE operations in io_init_req()
validated the logical SQ head position rather than the physical SQE
index.
The existing check:
!(ctx->cached_sq_head & (ctx->sq_entries - 1))
ensures the logical position isn't at the end of the ring, which is
correct for NO_SQARRAY rings where physical == logical. However, when
sq_array is present, an unprivileged user can remap any logical
position to an arbitrary physical index via sq_array. Setting
sq_array[N] = sq_entries - 1 places a 128-byte operation at the last
physical SQE slot, causing the 128-byte memcpy in
io_uring_cmd_sqe_copy() to read 64 bytes past the end of the SQE
array.
Replace the cached_sq_head alignment check with a direct validation
of the physical SQE index, which correctly handles both sq_array and
NO_SQARRAY cases.
Fixes: 1cba30bf9fdd ("io_uring: add support for IORING_SETUP_SQE_MIXED")
Signed-off-by: Tom Ryan <ryan36005@gmail.com>
Link: https://patch.msgid.link/20260310052003.72871-1-ryan36005@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/io_uring.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 20fdc442e014..20ec8fdafcae 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1745,7 +1745,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, * well as 2 contiguous entries. */ if (!(ctx->flags & IORING_SETUP_SQE_MIXED) || *left < 2 || - !(ctx->cached_sq_head & (ctx->sq_entries - 1))) + (unsigned)(sqe - ctx->sq_sqes) >= ctx->sq_entries - 1) return io_init_fail_req(req, -EINVAL); /* * A 128b operation on a mixed SQ uses two entries, so we have |