From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:55290) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ghW3h-00009G-5E for qemu-devel@nongnu.org; Thu, 10 Jan 2019 03:51:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ghVqm-00015j-TN for qemu-devel@nongnu.org; Thu, 10 Jan 2019 03:38:06 -0500 Received: from mout.kundenserver.de ([212.227.126.135]:46975) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1ghVqm-000157-44 for qemu-devel@nongnu.org; Thu, 10 Jan 2019 03:38:04 -0500 From: Laurent Vivier Date: Thu, 10 Jan 2019 09:37:37 +0100 Message-Id: <20190110083737.5036-3-laurent@vivier.eu> In-Reply-To: <20190110083737.5036-1-laurent@vivier.eu> References: <20190110083737.5036-1-laurent@vivier.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PULL 2/2] linux-user: make pwrite64/pread64(fd, NULL, 0, offset) return 0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Laurent Vivier , Riku Voipio , Peter Maydell , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= From: Peter Maydell Linux returns success if pwrite64() or pread64() are called with a zero length NULL buffer, but QEMU was returning -TARGET_EFAULT. This is the same bug that we fixed in commit 58cfa6c2e6eb51b23cc9 for the write syscall, and long before that in 38d840e6790c29f59 for the read syscall. Fixes: https://bugs.launchpad.net/qemu/+bug/1810433 Signed-off-by: Peter Maydell Reviewed-by: Laurent Vivier Reviewed-by: Philippe Mathieu-Daudé Message-Id: <20190108184900.9654-1-peter.maydell@linaro.org> Signed-off-by: Laurent Vivier --- linux-user/syscall.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 29bac79b61..d6605b8b50 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -9716,8 +9716,15 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, arg4 = arg5; arg5 = arg6; } - if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0))) - return -TARGET_EFAULT; + if (arg2 == 0 && arg3 == 0) { + /* Special-case NULL buffer and zero length, which should succeed */ + p = 0; + } else { + p = lock_user(VERIFY_WRITE, arg2, arg3, 0); + if (!p) { + return -TARGET_EFAULT; + } + } ret = get_errno(pread64(arg1, p, arg3, target_offset64(arg4, arg5))); unlock_user(p, arg2, ret); return ret; @@ -9726,8 +9733,15 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, arg4 = arg5; arg5 = arg6; } - if (!(p = lock_user(VERIFY_READ, arg2, arg3, 1))) - return -TARGET_EFAULT; + if (arg2 == 0 && arg3 == 0) { + /* Special-case NULL buffer and zero length, which should succeed */ + p = 0; + } else { + p = lock_user(VERIFY_READ, arg2, arg3, 1); + if (!p) { + return -TARGET_EFAULT; + } + } ret = get_errno(pwrite64(arg1, p, arg3, target_offset64(arg4, arg5))); unlock_user(p, arg2, 0); return ret; -- 2.20.1