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

From: Andreas Gruenbacher
Date: Mon Apr 20 2020 - 08:51:59 EST


Am Mo., 20. Apr. 2020 um 14:15 Uhr schrieb Trond Myklebust <trondmy@xxxxxxxxxxxxxxx>:
> I don't really see any alternative to adding a 'dfalloc' to track the
> allocated dfacl separately.

Something like the attached patch should work as well.

Thanks,
Andreas

---
fs/nfs/nfs3acl.c | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index c5c3fc6e6c60..f1581f11c220 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -253,37 +253,41 @@ 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;
int status;

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

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

if (acl == NULL) {
- alloc = acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
- if (IS_ERR(alloc))
- goto fail;
+ acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
+ status = PTR_ERR(acl);
+ if (IS_ERR(acl))
+ goto out;
}
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);
}

const struct xattr_handler *nfs3_xattr_handlers[] = {

base-commit: ae83d0b416db002fe95601e7f97f64b59514d936
--
2.25.3