2020-04-20 15:02:11

by Andreas Gruenbacher

Subject: [PATCH] nfs: Fix potential posix_acl refcnt leak in nfs3_set_acl

nfs3_set_acl keeps track of the acl it allocated locally to determine if an acl
needs to be released at the end. This results in a memory leak when the
function allocates an acl as well as a default acl. Fix by releasing acls
that differ from the acl originally passed into nfs3_set_acl.

Fixes: b7fa0554cf1b ("[PATCH] NFS: Add support for NFSv3 ACLs")
Reported-by: Xiyu Yang <[email protected]>
Signed-off-by: Andreas Gruenbacher <[email protected]>
---
fs/nfs/nfs3acl.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index c5c3fc6e6c60..26c94b32d6f4 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -253,37 +253,45 @@ int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,

int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int type)
{
- struct posix_acl *alloc = NULL, *dfacl = NULL;
+ struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
int status;

if (S_ISDIR(inode->i_mode)) {
switch(type) {
case ACL_TYPE_ACCESS:
- alloc = dfacl = get_acl(inode, ACL_TYPE_DEFAULT);
+ alloc = get_acl(inode, ACL_TYPE_DEFAULT);
if (IS_ERR(alloc))
goto fail;
+ dfacl = alloc;
break;

case ACL_TYPE_DEFAULT:
- dfacl = acl;
- alloc = acl = get_acl(inode, ACL_TYPE_ACCESS);
+ alloc = get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(alloc))
goto fail;
+ dfacl = acl;
+ acl = alloc;
break;
}
}

if (acl == NULL) {
- alloc = acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
+ alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
if (IS_ERR(alloc))
goto fail;
+ acl = alloc;
}
status = __nfs3_proc_setacls(inode, acl, dfacl);
- posix_acl_release(alloc);
+out:
+ if (acl != orig)
+ posix_acl_release(acl);
+ if (dfacl != orig)
+ posix_acl_release(dfacl);
return status;

fail:
- return PTR_ERR(alloc);
+ status = PTR_ERR(alloc);
+ goto out;
}

const struct xattr_handler *nfs3_xattr_handlers[] = {

base-commit: ae83d0b416db002fe95601e7f97f64b59514d936
--
2.25.3

2020-04-20 15:11:40

by Trond Myklebust

Subject: Re: [PATCH] nfs: Fix potential posix_acl refcnt leak in nfs3_set_acl

On Mon, 2020-04-20 at 15:51 +0200, Andreas Gruenbacher wrote:
> nfs3_set_acl keeps track of the acl it allocated locally to determine
> if an acl
> needs to be released at the end. This results in a memory leak when
> the
> function allocates an acl as well as a default acl. Fix by releasing
> acls
> that differ from the acl originally passed into nfs3_set_acl.
>
> Fixes: b7fa0554cf1b ("[PATCH] NFS: Add support for NFSv3 ACLs")
> Reported-by: Xiyu Yang <[email protected]>
> Signed-off-by: Andreas Gruenbacher <[email protected]>
> ---
> fs/nfs/nfs3acl.c | 22 +++++++++++++++-------
> 1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
> index c5c3fc6e6c60..26c94b32d6f4 100644
> --- a/fs/nfs/nfs3acl.c
> +++ b/fs/nfs/nfs3acl.c
> @@ -253,37 +253,45 @@ int nfs3_proc_setacls(struct inode *inode,
> struct posix_acl *acl,
>
> int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int
> type)
> {
> - struct posix_acl *alloc = NULL, *dfacl = NULL;
> + struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
> int status;
>
> if (S_ISDIR(inode->i_mode)) {
> switch(type) {
> case ACL_TYPE_ACCESS:
> - alloc = dfacl = get_acl(inode,
> ACL_TYPE_DEFAULT);
> + alloc = get_acl(inode, ACL_TYPE_DEFAULT);
> if (IS_ERR(alloc))
> goto fail;
> + dfacl = alloc;
> break;
>
> case ACL_TYPE_DEFAULT:
> - dfacl = acl;
> - alloc = acl = get_acl(inode, ACL_TYPE_ACCESS);
> + alloc = get_acl(inode, ACL_TYPE_ACCESS);
> if (IS_ERR(alloc))
> goto fail;
> + dfacl = acl;
> + acl = alloc;
> break;
> }
> }
>
> if (acl == NULL) {
> - alloc = acl = posix_acl_from_mode(inode->i_mode,
> GFP_KERNEL);
> + alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
> if (IS_ERR(alloc))
> goto fail;
> + acl = alloc;
> }
> status = __nfs3_proc_setacls(inode, acl, dfacl);
> - posix_acl_release(alloc);
> +out:
> + if (acl != orig)
> + posix_acl_release(acl);
> + if (dfacl != orig)
> + posix_acl_release(dfacl);
> return status;
>
> fail:
> - return PTR_ERR(alloc);
> + status = PTR_ERR(alloc);
> + goto out;
> }
>
> const struct xattr_handler *nfs3_xattr_handlers[] = {
>
> base-commit: ae83d0b416db002fe95601e7f97f64b59514d936

Thanks Andreas! This one looks good.

--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
[email protected]