From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AD47828C87C; Wed, 8 Apr 2026 18:33:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673230; cv=none; b=Qk9oQ6HqSpO4Sip5wKx4SK/4BTWmRGvSWjbluhGg8Wp5lYxnJzCYAWqDbOYUSNoLfNA+2e3Wk+MFa4opjI9A18EYRivdQwAujH675vWKPQrPt0uYfylBYyo5SK98CgN888R5ZKMG3tfQnMrbZlOILIJLe4JJZxvbI++3+XBTNos= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673230; c=relaxed/simple; bh=n94ePdRURFuQ7aw8RLkIOtgIQQjEvLYkmkSgDsUz9SA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gt4/eyPnEvinvxclnVas8lvLpSUhu9jtsLaKlUz9TK6e9fo76xGEYGBmxapYclmZI/Ec4bBCSvqvpGIlmS7gd/avvOit5pcPVjHflB339V9hbOPL/QBVB+p5XvGBH0LnaXYy35f571C7bNebNuspqGJduLBXSU6PorazvhHtctw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AAhCM2eG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AAhCM2eG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45271C19421; Wed, 8 Apr 2026 18:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775673230; bh=n94ePdRURFuQ7aw8RLkIOtgIQQjEvLYkmkSgDsUz9SA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AAhCM2eGrsAtw94tRqTr749VxjhDLBXexiHKKPPA77KN27y185vy5SzkgSCIiG6r4 uKiw3WyzwtJYZR6pHs78uP3vCi5Le3ocBnUykVZD3zoJNBy+CBMwEqsDBZUZw+0IRq Eh6G2nCqbqKzT4nkKGnsWQHu3dJZIS7PdwyPshxs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Qi Tang , Jens Axboe , Sasha Levin Subject: [PATCH 6.18 108/277] io_uring/rsrc: reject zero-length fixed buffer import Date: Wed, 8 Apr 2026 20:01:33 +0200 Message-ID: <20260408175937.905221900@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175933.836769063@linuxfoundation.org> References: <20260408175933.836769063@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qi Tang [ Upstream commit 111a12b422a8cfa93deabaef26fec48237163214 ] validate_fixed_range() admits buf_addr at the exact end of the registered region when len is zero, because the check uses strict greater-than (buf_end > imu->ubuf + imu->len). io_import_fixed() then computes offset == imu->len, which causes the bvec skip logic to advance past the last bio_vec entry and read bv_offset from out-of-bounds slab memory. Return early from io_import_fixed() when len is zero. A zero-length import has no data to transfer and should not walk the bvec array at all. BUG: KASAN: slab-out-of-bounds in io_import_reg_buf+0x697/0x7f0 Read of size 4 at addr ffff888002bcc254 by task poc/103 Call Trace: io_import_reg_buf+0x697/0x7f0 io_write_fixed+0xd9/0x250 __io_issue_sqe+0xad/0x710 io_issue_sqe+0x7d/0x1100 io_submit_sqes+0x86a/0x23c0 __do_sys_io_uring_enter+0xa98/0x1590 Allocated by task 103: The buggy address is located 12 bytes to the right of allocated 584-byte region [ffff888002bcc000, ffff888002bcc248) Fixes: 8622b20f23ed ("io_uring: add validate_fixed_range() for validate fixed buffer") Signed-off-by: Qi Tang Link: https://patch.msgid.link/20260329164936.240871-1-tpluszz77@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- io_uring/rsrc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 44442bf4827e4..dc87c6a86e346 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -1082,6 +1082,10 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, return ret; if (!(imu->dir & (1 << ddir))) return -EFAULT; + if (unlikely(!len)) { + iov_iter_bvec(iter, ddir, NULL, 0, 0); + return 0; + } offset = buf_addr - imu->ubuf; -- 2.53.0