[PATCH 2/2] afs: Fix afs_xattr_get_yfs() to not try freeing an error value

David Howells
2019-05-12T07:45:48Z

afs_xattr_get_yfs() tries to free yacl, which may hold an error value (say
if yfs_fs_fetch_opaque_acl() failed and returned an error).

Fix this by allocating yacl up front (since it's a fixed-length struct,
unlike afs_acl) and passing it in to the RPC function. This also allows
the flags to be placed in the object rather than passing them through to
the RPC function.

Fixes: ae46578b963f ("afs: Get YFS ACLs and information through xattrs")
Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/afs/internal.h | 2 +
fs/afs/xattr.c | 86 ++++++++++++++++++++++++++++------------------------
fs/afs/yfsclient.c | 29 ++++--------------
3 files changed, 53 insertions(+), 64 deletions(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index b3cd6e8ad59d..74ee0f8ef8dd 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1382,7 +1382,7 @@ struct yfs_acl {
};

extern void yfs_free_opaque_acl(struct yfs_acl *);
-extern struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *, unsigned int);
+extern struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *, struct yfs_acl *);
extern int yfs_fs_store_opaque_acl2(struct afs_fs_cursor *, const struct afs_acl *);

/*
diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
index b6c44e75b361..d12bcda911e1 100644
--- a/fs/afs/xattr.c
+++ b/fs/afs/xattr.c
@@ -148,9 +148,8 @@ static int afs_xattr_get_yfs(const struct xattr_handler *handler,
struct afs_vnode *vnode = AFS_FS_I(inode);
struct yfs_acl *yacl = NULL;
struct key *key;
- unsigned int flags = 0;
char buf[16], *data;
- int which = 0, dsize, ret;
+ int which = 0, dsize, ret = -ENOMEM;

if (strcmp(name, "acl") = 0)
which = 0;
@@ -163,20 +162,26 @@ static int afs_xattr_get_yfs(const struct xattr_handler *handler,
else
return -EOPNOTSUPP;

+ yacl = kzalloc(sizeof(struct yfs_acl), GFP_KERNEL);
+ if (!yacl)
+ goto error;
+
if (which = 0)
- flags |= YFS_ACL_WANT_ACL;
+ yacl->flags |= YFS_ACL_WANT_ACL;
else if (which = 3)
- flags |= YFS_ACL_WANT_VOL_ACL;
+ yacl->flags |= YFS_ACL_WANT_VOL_ACL;

key = afs_request_key(vnode->volume->cell);
- if (IS_ERR(key))
- return PTR_ERR(key);
+ if (IS_ERR(key)) {
+ ret = PTR_ERR(key);
+ goto error_yacl;
+ }

ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key)) {
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
- yacl = yfs_fs_fetch_opaque_acl(&fc, flags);
+ yfs_fs_fetch_opaque_acl(&fc, yacl);
}

afs_check_for_remote_deletion(&fc, fc.vnode);
@@ -184,44 +189,45 @@ static int afs_xattr_get_yfs(const struct xattr_handler *handler,
ret = afs_end_vnode_operation(&fc);
}

- if (ret = 0) {
- switch (which) {
- case 0:
- data = yacl->acl->data;
- dsize = yacl->acl->size;
- break;
- case 1:
- data = buf;
- dsize = snprintf(buf, sizeof(buf), "%u",
- yacl->inherit_flag);
- break;
- case 2:
- data = buf;
- dsize = snprintf(buf, sizeof(buf), "%u",
- yacl->num_cleaned);
- break;
- case 3:
- data = yacl->vol_acl->data;
- dsize = yacl->vol_acl->size;
- break;
- default:
- ret = -EOPNOTSUPP;
- goto out;
- }
+ if (ret < 0)
+ goto error_key;
+
+ switch (which) {
+ case 0:
+ data = yacl->acl->data;
+ dsize = yacl->acl->size;
+ break;
+ case 1:
+ data = buf;
+ dsize = snprintf(buf, sizeof(buf), "%u", yacl->inherit_flag);
+ break;
+ case 2:
+ data = buf;
+ dsize = snprintf(buf, sizeof(buf), "%u", yacl->num_cleaned);
+ break;
+ case 3:
+ data = yacl->vol_acl->data;
+ dsize = yacl->vol_acl->size;
+ break;
+ default:
+ ret = -EOPNOTSUPP;
+ goto error_key;
+ }

- ret = dsize;
- if (size > 0) {
- if (dsize > size) {
- ret = -ERANGE;
- goto out;
- }
- memcpy(buffer, data, dsize);
+ ret = dsize;
+ if (size > 0) {
+ if (dsize > size) {
+ ret = -ERANGE;
+ goto error_key;
}
+ memcpy(buffer, data, dsize);
}

-out:
- yfs_free_opaque_acl(yacl);
+error_key:
key_put(key);
+error_yacl:
+ yfs_free_opaque_acl(yacl);
+error:
return ret;
}

diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index 6cf7d161baa1..d3e9e3fe0b58 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -2333,12 +2333,6 @@ void yfs_free_opaque_acl(struct yfs_acl *yacl)
}
}

-static void yfs_destroy_fs_fetch_opaque_acl(struct afs_call *call)
-{
- yfs_free_opaque_acl(call->reply[0]);
- afs_flat_call_destructor(call);
-}
-
/*
* YFS.FetchOpaqueACL operation type
*/
@@ -2346,18 +2340,17 @@ static const struct afs_call_type yfs_RXYFSFetchOpaqueACL = {
.name = "YFS.FetchOpaqueACL",
.op = yfs_FS_FetchOpaqueACL,
.deliver = yfs_deliver_fs_fetch_opaque_acl,
- .destructor = yfs_destroy_fs_fetch_opaque_acl,
+ .destructor = afs_flat_call_destructor,
};

/*
* Fetch the YFS advanced ACLs for a file.
*/
struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *fc,
- unsigned int flags)
+ struct yfs_acl *yacl)
{
struct afs_vnode *vnode = fc->vnode;
struct afs_call *call;
- struct yfs_acl *yacl;
struct afs_net *net = afs_v2net(vnode);
__be32 *bp;

@@ -2370,19 +2363,15 @@ struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *fc,
sizeof(__be32) * 2 +
sizeof(struct yfs_xdr_YFSFetchStatus) +
sizeof(struct yfs_xdr_YFSVolSync));
- if (!call)
- goto nomem;
-
- yacl = kzalloc(sizeof(struct yfs_acl), GFP_KERNEL);
- if (!yacl)
- goto nomem_call;
+ if (!call) {
+ fc->ac.error = -ENOMEM;
+ return ERR_PTR(-ENOMEM);
+ }

- yacl->flags = flags;
call->key = fc->key;
call->reply[0] = yacl;
call->reply[1] = vnode;
call->reply[2] = NULL; /* volsync */
- call->ret_reply0 = true;

/* marshall the parameters */
bp = call->request;
@@ -2396,12 +2385,6 @@ struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *fc,
trace_afs_make_fs_call(call, &vnode->fid);
afs_make_call(&fc->ac, call, GFP_KERNEL);
return (struct yfs_acl *)afs_wait_for_call_to_complete(call, &fc->ac);
-
-nomem_call:
- afs_put_call(call);
-nomem:
- fc->ac.error = -ENOMEM;
- return ERR_PTR(-ENOMEM);
}

/*