2021-01-06 00:15:12

by Tom Rix

Subject: [PATCH] cifs: check pointer before freeing

From: Tom Rix <[email protected]>

clang static analysis reports this problem

dfs_cache.c:591:2: warning: Argument to kfree() is a constant address
(18446744073709551614), which is not memory allocated by malloc()
kfree(vi);
^~~~~~~~~

In dfs_cache_del_vol() the volume info pointer 'vi' being freed
is the return of a call to find_vol(). The large constant address
is find_vol() returning an error.

Add an error check to dfs_cache_del_vol() similar to the one done
in dfs_cache_update_vol().

Fixes: 54be1f6c1c37 ("cifs: Add DFS cache routines")
Signed-off-by: Tom Rix <[email protected]>
---
fs/cifs/dfs_cache.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
index 6ad6ba5f6ebe..0fdb0de7ff86 100644
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath)
vi = find_vol(fullpath);
spin_unlock(&vol_list_lock);

- kref_put(&vi->refcnt, vol_release);
+ if (!IS_ERR(vi))
+ kref_put(&vi->refcnt, vol_release);
}

/**
--
2.27.0

2021-01-06 00:46:07

by Nathan Chancellor

Subject: Re: [PATCH] cifs: check pointer before freeing

On Tue, Jan 05, 2021 at 12:21:26PM -0800, [email protected] wrote:
> From: Tom Rix <[email protected]>
>
> clang static analysis reports this problem
>
> dfs_cache.c:591:2: warning: Argument to kfree() is a constant address
> (18446744073709551614), which is not memory allocated by malloc()
> kfree(vi);
> ^~~~~~~~~
>
> In dfs_cache_del_vol() the volume info pointer 'vi' being freed
> is the return of a call to find_vol(). The large constant address
> is find_vol() returning an error.
>
> Add an error check to dfs_cache_del_vol() similar to the one done
> in dfs_cache_update_vol().
>
> Fixes: 54be1f6c1c37 ("cifs: Add DFS cache routines")
> Signed-off-by: Tom Rix <[email protected]>

Reviewed-by: Nathan Chancellor <[email protected]>

> ---
> fs/cifs/dfs_cache.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
> index 6ad6ba5f6ebe..0fdb0de7ff86 100644
> --- a/fs/cifs/dfs_cache.c
> +++ b/fs/cifs/dfs_cache.c
> @@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath)
> vi = find_vol(fullpath);
> spin_unlock(&vol_list_lock);
>
> - kref_put(&vi->refcnt, vol_release);
> + if (!IS_ERR(vi))
> + kref_put(&vi->refcnt, vol_release);
> }
>
> /**
> --
> 2.27.0
>

2021-01-06 04:14:15

by Steve French

Subject: Re: [PATCH] cifs: check pointer before freeing

merged into cifs-2.6.git for-next and added cc:stable

On Tue, Jan 5, 2021 at 5:08 PM Nathan Chancellor
<[email protected]> wrote:
>
> On Tue, Jan 05, 2021 at 12:21:26PM -0800, [email protected] wrote:
> > From: Tom Rix <[email protected]>
> >
> > clang static analysis reports this problem
> >
> > dfs_cache.c:591:2: warning: Argument to kfree() is a constant address
> > (18446744073709551614), which is not memory allocated by malloc()
> > kfree(vi);
> > ^~~~~~~~~
> >
> > In dfs_cache_del_vol() the volume info pointer 'vi' being freed
> > is the return of a call to find_vol(). The large constant address
> > is find_vol() returning an error.
> >
> > Add an error check to dfs_cache_del_vol() similar to the one done
> > in dfs_cache_update_vol().
> >
> > Fixes: 54be1f6c1c37 ("cifs: Add DFS cache routines")
> > Signed-off-by: Tom Rix <[email protected]>
>
> Reviewed-by: Nathan Chancellor <[email protected]>
>
> > ---
> > fs/cifs/dfs_cache.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
> > index 6ad6ba5f6ebe..0fdb0de7ff86 100644
> > --- a/fs/cifs/dfs_cache.c
> > +++ b/fs/cifs/dfs_cache.c
> > @@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath)
> > vi = find_vol(fullpath);
> > spin_unlock(&vol_list_lock);
> >
> > - kref_put(&vi->refcnt, vol_release);
> > + if (!IS_ERR(vi))
> > + kref_put(&vi->refcnt, vol_release);
> > }
> >
> > /**
> > --
> > 2.27.0
> >



--
Thanks,

Steve