From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pl1-x644.google.com ([2607:f8b0:4864:20::644]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gm776-0007Tr-Ap for barebox@lists.infradead.org; Wed, 23 Jan 2019 01:14:00 +0000 Received: by mail-pl1-x644.google.com with SMTP id e11so242210plt.11 for ; Tue, 22 Jan 2019 17:13:56 -0800 (PST) From: Andrey Smirnov Date: Tue, 22 Jan 2019 17:13:35 -0800 Message-Id: <20190123011338.32517-5-andrew.smirnov@gmail.com> In-Reply-To: <20190123011338.32517-1-andrew.smirnov@gmail.com> References: <20190123011338.32517-1-andrew.smirnov@gmail.com> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH 4/7] fs: Change error checking logic for fsdrv->lseek() call To: barebox@lists.infradead.org Cc: Andrey Smirnov On 32-bit systems, cheking for IS_ERR_VALUE(pos) is not correct. Expanding that code we get (loff_t cast is added for clarity): (loff_t)pos >= (unsigned long)-MAX_ERRNO given that loff_t is a 64-bit signed value, any perfectly valid seek offset that is greater than 0xffffc000 will result in false positive. Change the logic to check if position returned by fsdrv->lseek() is what's been requested. If it is, we can assume that operation was succesfull. If not, that's likely means failure and return value is a negative error code. This should accomodate both 32-bit systems, where we /dev/mem doesn't present any range problems, as well as 64-bit systems where both file offset and size of /dev/mem couldn't really be correctly captured by loff_t and we have to rely on 2's complement and overflow. Signed-off-by: Andrey Smirnov --- fs/fs.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/fs/fs.c b/fs/fs.c index a304bf186..6a62fb98b 100644 --- a/fs/fs.c +++ b/fs/fs.c @@ -405,8 +405,7 @@ loff_t lseek(int fildes, loff_t offset, int whence) { struct fs_driver_d *fsdrv; FILE *f; - loff_t pos; - int ret; + loff_t pos, ret; if (check_fd(fildes)) return -1; @@ -442,13 +441,11 @@ loff_t lseek(int fildes, loff_t offset, int whence) goto out; } - pos = fsdrv->lseek(&f->fsdev->dev, f, pos); - if (IS_ERR_VALUE(pos)) { - errno = -pos; - return -1; - } + ret = fsdrv->lseek(&f->fsdev->dev, f, pos); + if (ret != pos) + goto out; - return pos; + return ret; out: if (ret) -- 2.20.1 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox