Commit 5170efd9 authored by Nicholas Carlini's avatar Nicholas Carlini Committed by Jens Axboe
Browse files

io_uring/fdinfo: fix OOB read in SQE_MIXED wrap check 



__io_uring_show_fdinfo() iterates over pending SQEs and, for 128-byte
SQEs on an IORING_SETUP_SQE_MIXED ring, needs to detect when the second
half of the SQE would be past the end of the sq_sqes array. The current
check tests (++sq_head & sq_mask) == 0, but sq_head is only incremented
when a 128-byte SQE is encountered, not on every iteration. The actual
array index is sq_idx = (i + sq_head) & sq_mask, which can be sq_mask
(the last slot) while the wrap check passes.

Fix by checking sq_idx directly. Keep the sq_head increment so the loop
still skips the second half of the 128-byte SQE on the next iteration.

Fixes: 1cba30bf ("io_uring: add support for IORING_SETUP_SQE_MIXED")
Signed-off-by: default avatarNicholas Carlini <nicholas@carlini.com>
Link: https://patch.msgid.link/20260327021823.3138396-1-nicholas@carlini.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b59efde9

io_uring/fdinfo.c

+2 −1
Original line number Diff line number Diff line
@@ -119,12 +119,13 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) 
					sq_idx);

				break;

			}

			if ((++sq_head & sq_mask) == 0) {

			if (sq_idx == sq_mask) {

				seq_printf(m,

					"%5u: corrupted sqe, wrapping 128B entry\n",

					sq_idx);

				break;

			}

			sq_head++;

			i++;

			sqe128 = true;

		}