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io_uring: always grab file table for deferred statx

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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.

Link: https://lore.kernel.org/io-uring/YoOJ%2FT4QRKC+fAZE@google.com/
Reported-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Axboe
2022-05-19 06:05:27 -06:00
committed by Greg Kroah-Hartman
parent a1a2c957da
commit 3c48558be5
1 changed files with 1 additions and 5 deletions
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6
fs/io_uring.c
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@@ -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);