From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, virtio-fs@redhat.com,
miklos@szeredi.hu, linux-kernel@vger.kernel.org,
dan.carpenter@oracle.com
Subject: Re: [PATCH 1/2] virtiofs, dax: Fix smatch warning about loss of info during shift
Date: Thu, 6 May 2021 20:07:39 +0100 [thread overview]
Message-ID: <YJQ+ex2DUPYo1GV5@work-vm> (raw)
In-Reply-To: <20210506184304.321645-2-vgoyal@redhat.com>
* Vivek Goyal (vgoyal@redhat.com) wrote:
> Dan reported a smatch warning during potentential loss of info during
> left shift if this code is compiled on 32bit systems.
>
> New smatch warnings:
> fs/fuse/dax.c:113 fuse_setup_one_mapping() warn: should 'start_idx << 21' be a
> +64 bit type?
>
> I ran smatch and found two more instances of similar warning. This patch
> fixes all such instances.
>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
> fs/fuse/dax.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> index ff99ab2a3c43..f06fdad3f7b1 100644
> --- a/fs/fuse/dax.c
> +++ b/fs/fuse/dax.c
> @@ -186,7 +186,7 @@ static int fuse_setup_one_mapping(struct inode *inode, unsigned long start_idx,
> struct fuse_conn_dax *fcd = fm->fc->dax;
> struct fuse_inode *fi = get_fuse_inode(inode);
> struct fuse_setupmapping_in inarg;
> - loff_t offset = start_idx << FUSE_DAX_SHIFT;
> + loff_t offset = (loff_t)start_idx << FUSE_DAX_SHIFT;
I've not followed the others back, but isn't it easier to change
the start_idx parameter to be a loff_t, since the places it's called
from are poth loff_t pos?
Dave
> FUSE_ARGS(args);
> ssize_t err;
>
> @@ -872,7 +872,7 @@ static int dmap_writeback_invalidate(struct inode *inode,
> struct fuse_dax_mapping *dmap)
> {
> int ret;
> - loff_t start_pos = dmap->itn.start << FUSE_DAX_SHIFT;
> + loff_t start_pos = (loff_t)dmap->itn.start << FUSE_DAX_SHIFT;
> loff_t end_pos = (start_pos + FUSE_DAX_SZ - 1);
>
> ret = filemap_fdatawrite_range(inode->i_mapping, start_pos, end_pos);
> @@ -966,7 +966,7 @@ inode_inline_reclaim_one_dmap(struct fuse_conn_dax *fcd, struct inode *inode,
> dmap = inode_lookup_first_dmap(inode);
> if (dmap) {
> start_idx = dmap->itn.start;
> - dmap_start = start_idx << FUSE_DAX_SHIFT;
> + dmap_start = (u64)start_idx << FUSE_DAX_SHIFT;
> dmap_end = dmap_start + FUSE_DAX_SZ - 1;
> }
> up_read(&fi->dax->sem);
> @@ -1118,7 +1118,7 @@ static int lookup_and_reclaim_dmap(struct fuse_conn_dax *fcd,
> {
> int ret;
> struct fuse_inode *fi = get_fuse_inode(inode);
> - loff_t dmap_start = start_idx << FUSE_DAX_SHIFT;
> + loff_t dmap_start = (loff_t)start_idx << FUSE_DAX_SHIFT;
> loff_t dmap_end = (dmap_start + FUSE_DAX_SZ) - 1;
>
> down_write(&fi->i_mmap_sem);
> --
> 2.25.4
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2021-05-06 19:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 18:43 [PATCH 0/2] virtiofs, dax: Fix couple of smatch warnings Vivek Goyal
2021-05-06 18:43 ` [PATCH 1/2] virtiofs, dax: Fix smatch warning about loss of info during shift Vivek Goyal
2021-05-06 19:07 ` Dr. David Alan Gilbert [this message]
2021-05-06 19:35 ` Matthew Wilcox
2021-05-10 18:16 ` Vivek Goyal
2021-05-06 18:43 ` [PATCH 2/2] virtiofs, dax: Fixed smatch warning about ret being uninitialized Vivek Goyal
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