[PATCH] smbfs_client: fix a sign extension bug

[PATCH] smbfs_client: fix a sign extension bug

[Dan Carpenter]

The problem is the mismatched types between "ctx->total_len" which is
an unsigned int, "rc" which is an int, and "ctx->rc" which is a
ssize_t.  The code does:

	ctx->rc = (rc == 0) ? ctx->total_len : rc;

We want "ctx->rc" to store the negative "rc" error code.  But what
happens is that "rc" is type promoted to a high unsigned int and
'ctx->rc" will store the high positive value instead of a negative
value.

The fix is to change "rc" from an int to a ssize_t.

Fixes: c610c4b619e5 ("CIFS: Add asynchronous write support through kernel AIO")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 fs/smbfs_client/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/smbfs_client/file.c b/fs/smbfs_client/file.c
index 4d10c9343890..7db9ddb3381f 100644
--- a/fs/smbfs_client/file.c
+++ b/fs/smbfs_client/file.c
@@ -3111,7 +3111,7 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
 	struct cifs_tcon *tcon;
 	struct cifs_sb_info *cifs_sb;
 	struct dentry *dentry = ctx->cfile->dentry;
-	int rc;
+	ssize_t rc;
 
 	tcon = tlink_tcon(ctx->cfile->tlink);
 	cifs_sb = CIFS_SB(dentry->d_sb);
-- 
2.20.1

Re: [PATCH] smbfs_client: fix a sign extension bug

[Steve French]

merged into cifs-2.6.git for-next

On Tue, Sep 21, 2021 at 4:13 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> The problem is the mismatched types between "ctx->total_len" which is
> an unsigned int, "rc" which is an int, and "ctx->rc" which is a
> ssize_t.  The code does:
>
>         ctx->rc = (rc == 0) ? ctx->total_len : rc;
>
> We want "ctx->rc" to store the negative "rc" error code.  But what
> happens is that "rc" is type promoted to a high unsigned int and
> 'ctx->rc" will store the high positive value instead of a negative
> value.
>
> The fix is to change "rc" from an int to a ssize_t.
>
> Fixes: c610c4b619e5 ("CIFS: Add asynchronous write support through kernel AIO")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  fs/smbfs_client/file.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/smbfs_client/file.c b/fs/smbfs_client/file.c
> index 4d10c9343890..7db9ddb3381f 100644
> --- a/fs/smbfs_client/file.c
> +++ b/fs/smbfs_client/file.c
> @@ -3111,7 +3111,7 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
>         struct cifs_tcon *tcon;
>         struct cifs_sb_info *cifs_sb;
>         struct dentry *dentry = ctx->cfile->dentry;
> -       int rc;
> +       ssize_t rc;
>
>         tcon = tlink_tcon(ctx->cfile->tlink);
>         cifs_sb = CIFS_SB(dentry->d_sb);
> --
> 2.20.1
>


-- 
Thanks,

Steve