From 843d3cb41b0f9408e1f1bcbb7e4fda081b9ca5f1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 19 May 2022 06:05:27 -0600 Subject: [PATCH] BACKPORT: io_uring: always grab file table for deferred statx Lee reports that there's a use-after-free of the process file table. There's an assumption that we don't need the file table for some variants of statx invocation, but that turns out to be false and we end up with not grabbing a reference for the request even if the deferred execution uses it. Get rid of the REQ_F_NO_FILE_TABLE optimization for statx, and always grab that reference. This issues doesn't exist upstream since the native workers got introduced with 5.12. Bug: 220738351 Link: https://lore.kernel.org/io-uring/YoOJ%2FT4QRKC+fAZE@google.com/ Reported-by: Lee Jones Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 3c48558be571e01f67e65edcf03193484eeb2b79) Signed-off-by: Lee Jones Change-Id: Ife51536d95368bffdc393ad2a5e737a0e6ddf18f --- fs/io_uring.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index d63d8713a197..b08d1089731c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4252,12 +4252,8 @@ static int io_statx(struct io_kiocb *req, bool force_nonblock) struct io_statx *ctx = &req->statx; int ret; - if (force_nonblock) { - /* only need file table for an actual valid fd */ - if (ctx->dfd == -1 || ctx->dfd == AT_FDCWD) - req->flags |= REQ_F_NO_FILE_TABLE; + if (force_nonblock) return -EAGAIN; - } ret = do_statx(ctx->dfd, ctx->filename, ctx->flags, ctx->mask, ctx->buffer);