fs/nfs/nfs4client.c | 10 +++++++++- fs/nfs/nfs4proc.c | 12 ++++++++++-- fs/nfs/super.c | 12 +++++++++--- include/linux/nfs_fs_sb.h | 2 +- include/linux/nfs_xdr.h | 1 + 5 files changed, 30 insertions(+), 7 deletions(-)
When performing exchange id call, a new nfs41_impl_id will be allocated to
store some information from server. The pointers to the old and new
nfs41_impl_ids are swapped, and the old one will be freed.
However, UAF may be triggered as follows:
After T2 has got a pointer to the nfs41_impl_id, the nfs41_impl_id is
freed by T1 before it is used.
T1 T2
nfs4_proc_exchange_id
_nfs4_proc_exchange_id
nfs4_run_exchange_id
kzalloc // alloc nfs41_impl_id-B
rpc_run_task
nfs_show_stats
show_implementation_id
impl_id = nfss->nfs_client->cl_implid
// get alloc nfs41_impl_id-A
swap(clp->cl_implid, resp->impl_id)
rpc_put_task
...
nfs4_exchange_id_release
kfree // free nfs41_impl_id-A
impl_id->name // UAF
Fix this issue by using rcu to protect the nfs41_impl_id.
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
---
v1->v2:
Free nfs41_impl_id by call_rcu in nfs4_shutdown_client to resolve
warning.
fs/nfs/nfs4client.c | 10 +++++++++-
fs/nfs/nfs4proc.c | 12 ++++++++++--
fs/nfs/super.c | 12 +++++++++---
include/linux/nfs_fs_sb.h | 2 +-
include/linux/nfs_xdr.h | 1 +
5 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 83378f69b35e..1aee1cfb6f1f 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -281,6 +281,13 @@ static void nfs4_destroy_callback(struct nfs_client *clp)
nfs_callback_down(clp->cl_mvops->minor_version, clp->cl_net);
}
+static void nfs4_free_impl_id_rcu(struct rcu_head *head)
+{
+ struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
+
+ kfree(impl_id);
+}
+
static void nfs4_shutdown_client(struct nfs_client *clp)
{
if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
@@ -293,7 +300,8 @@ static void nfs4_shutdown_client(struct nfs_client *clp)
rpc_destroy_wait_queue(&clp->cl_rpcwaitq);
kfree(clp->cl_serverowner);
kfree(clp->cl_serverscope);
- kfree(clp->cl_implid);
+ if (clp->cl_implid)
+ call_rcu(&clp->cl_implid->__rcu_head, nfs4_free_impl_id_rcu);
kfree(clp->cl_owner_id);
}
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b8ffbe52ba15..6bb820bd205e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -8866,13 +8866,21 @@ struct nfs41_exchange_id_data {
struct nfs41_exchange_id_args args;
};
+static void nfs4_free_impl_id_rcu(struct rcu_head *head)
+{
+ struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
+
+ kfree(impl_id);
+}
+
static void nfs4_exchange_id_release(void *data)
{
struct nfs41_exchange_id_data *cdata =
(struct nfs41_exchange_id_data *)data;
nfs_put_client(cdata->args.client);
- kfree(cdata->res.impl_id);
+ if (cdata->res.impl_id)
+ call_rcu(&cdata->res.impl_id->__rcu_head, nfs4_free_impl_id_rcu);
kfree(cdata->res.server_scope);
kfree(cdata->res.server_owner);
kfree(cdata);
@@ -9034,7 +9042,7 @@ static int _nfs4_proc_exchange_id(struct nfs_client *clp, const struct cred *cre
swap(clp->cl_serverowner, resp->server_owner);
swap(clp->cl_serverscope, resp->server_scope);
- swap(clp->cl_implid, resp->impl_id);
+ resp->impl_id = rcu_replace_pointer(clp->cl_implid, resp->impl_id, 1);
/* Save the EXCHANGE_ID verifier session trunk tests */
memcpy(clp->cl_confirm.data, argp->verifier.data,
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 97b386032b71..6097dbe8e334 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -612,13 +612,19 @@ static void show_pnfs(struct seq_file *m, struct nfs_server *server)
static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
{
- if (nfss->nfs_client && nfss->nfs_client->cl_implid) {
- struct nfs41_impl_id *impl_id = nfss->nfs_client->cl_implid;
+ struct nfs_client *clp = nfss->nfs_client;
+ struct nfs41_impl_id *impl_id;
+
+ if (!clp)
+ return;
+ rcu_read_lock();
+ impl_id = rcu_dereference(clp->cl_implid);
+ if (impl_id)
seq_printf(m, "\n\timpl_id:\tname='%s',domain='%s',"
"date='%llu,%u'",
impl_id->name, impl_id->domain,
impl_id->date.seconds, impl_id->date.nseconds);
- }
+ rcu_read_unlock();
}
#else
#if IS_ENABLED(CONFIG_NFS_V4)
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 1df86ab98c77..29c98c9df42f 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -102,7 +102,7 @@ struct nfs_client {
bool cl_preserve_clid;
struct nfs41_server_owner *cl_serverowner;
struct nfs41_server_scope *cl_serverscope;
- struct nfs41_impl_id *cl_implid;
+ struct nfs41_impl_id __rcu *cl_implid;
/* nfs 4.1+ state protection modes: */
unsigned long cl_sp4_flags;
#define NFS_SP4_MACH_CRED_MINIMAL 1 /* Minimal sp4_mach_cred - state ops
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 45623af3e7b8..b3c96ea2a64b 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1374,6 +1374,7 @@ struct nfs41_impl_id {
char domain[NFS4_OPAQUE_LIMIT + 1];
char name[NFS4_OPAQUE_LIMIT + 1];
struct nfstime4 date;
+ struct rcu_head __rcu_head;
};
#define MAX_BIND_CONN_TO_SESSION_RETRIES 3
--
2.31.1Hi Li,
kernel test robot noticed the following build errors:
[auto build test ERROR on trondmy-nfs/linux-next]
[also build test ERROR on linus/master v6.11-rc5 next-20240830]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Li-Lingfeng/nfs-protect-nfs41_impl_id-by-rcu/20240829-213622
base: git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next
patch link: https://lore.kernel.org/r/20240829133743.1008788-1-lilingfeng3%40huawei.com
patch subject: [PATCH v2] nfs: protect nfs41_impl_id by rcu
config: x86_64-defconfig (https://download.01.org/0day-ci/archive/20240831/202408310936.nUVC9Uw3-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240831/202408310936.nUVC9Uw3-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408310936.nUVC9Uw3-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from include/linux/container_of.h:5,
from include/linux/list.h:5,
from include/linux/module.h:12,
from fs/nfs/nfs4client.c:6:
fs/nfs/nfs4client.c: In function 'nfs4_free_impl_id_rcu':
>> include/linux/container_of.h:20:54: error: invalid use of undefined type 'struct nfs41_impl_id'
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \
| ^~
include/linux/build_bug.h:78:56: note: in definition of macro '__static_assert'
78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
| ^~~~
include/linux/container_of.h:20:9: note: in expansion of macro 'static_assert'
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \
| ^~~~~~~~~~~~~
include/linux/container_of.h:20:23: note: in expansion of macro '__same_type'
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \
| ^~~~~~~~~~~
fs/nfs/nfs4client.c:286:41: note: in expansion of macro 'container_of'
286 | struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
| ^~~~~~~~~~~~
include/linux/compiler_types.h:451:27: error: expression in static assertion is not an integer
451 | #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: in definition of macro '__static_assert'
78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
| ^~~~
include/linux/container_of.h:20:9: note: in expansion of macro 'static_assert'
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \
| ^~~~~~~~~~~~~
include/linux/container_of.h:20:23: note: in expansion of macro '__same_type'
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \
| ^~~~~~~~~~~
fs/nfs/nfs4client.c:286:41: note: in expansion of macro 'container_of'
286 | struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
| ^~~~~~~~~~~~
In file included from include/uapi/linux/posix_types.h:5,
from include/uapi/linux/types.h:14,
from include/linux/types.h:6,
from include/linux/kasan-checks.h:5,
from include/asm-generic/rwonce.h:26,
from ./arch/x86/include/generated/asm/rwonce.h:1,
from include/linux/compiler.h:314,
from include/linux/build_bug.h:5,
from include/linux/container_of.h:5,
from include/linux/list.h:5,
from include/linux/module.h:12,
from fs/nfs/nfs4client.c:6:
>> include/linux/stddef.h:16:33: error: invalid use of undefined type 'struct nfs41_impl_id'
16 | #define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
| ^~~~~~~~~~~~~~~~~~
include/linux/container_of.h:23:28: note: in expansion of macro 'offsetof'
23 | ((type *)(__mptr - offsetof(type, member))); })
| ^~~~~~~~
fs/nfs/nfs4client.c:286:41: note: in expansion of macro 'container_of'
286 | struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
| ^~~~~~~~~~~~
fs/nfs/nfs4client.c: In function 'nfs4_shutdown_client':
>> fs/nfs/nfs4client.c:304:41: error: invalid use of undefined type 'struct nfs41_impl_id'
304 | call_rcu(&clp->cl_implid->__rcu_head, nfs4_free_impl_id_rcu);
| ^~
vim +20 include/linux/container_of.h
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 9
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 10 /**
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 11 * container_of - cast a member of a structure out to the containing structure
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 12 * @ptr: the pointer to the member.
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 13 * @type: the type of the container struct this is embedded in.
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 14 * @member: the name of the member within the struct.
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 15 *
7376e561fd2e01 Sakari Ailus 2022-10-24 16 * WARNING: any const qualifier of @ptr is lost.
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 17 */
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 18 #define container_of(ptr, type, member) ({ \
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 19 void *__mptr = (void *)(ptr); \
e1edc277e6f6df Rasmus Villemoes 2021-11-08 @20 static_assert(__same_type(*(ptr), ((type *)0)->member) || \
e1edc277e6f6df Rasmus Villemoes 2021-11-08 21 __same_type(*(ptr), void), \
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 22 "pointer type mismatch in container_of()"); \
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 23 ((type *)(__mptr - offsetof(type, member))); })
d2a8ebbf8192b8 Andy Shevchenko 2021-11-08 24
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Hi Li,
kernel test robot noticed the following build errors:
[auto build test ERROR on trondmy-nfs/linux-next]
[also build test ERROR on linus/master v6.11-rc5 next-20240830]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Li-Lingfeng/nfs-protect-nfs41_impl_id-by-rcu/20240829-213622
base: git://git.linux-nfs.org/projects/trondmy/linux-nfs.git linux-next
patch link: https://lore.kernel.org/r/20240829133743.1008788-1-lilingfeng3%40huawei.com
patch subject: [PATCH v2] nfs: protect nfs41_impl_id by rcu
config: i386-randconfig-001-20240830 (https://download.01.org/0day-ci/archive/20240830/202408302315.02P7HuVM-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240830/202408302315.02P7HuVM-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408302315.02P7HuVM-lkp@intel.com/
All errors (new ones prefixed by >>):
>> fs/nfs/nfs4client.c:286:34: error: incomplete definition of type 'struct nfs41_impl_id'
286 | struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/container_of.h:20:47: note: expanded from macro 'container_of'
20 | static_assert(__same_type(*(ptr), ((type *)0)->member) || \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
21 | __same_type(*(ptr), void), \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
22 | "pointer type mismatch in container_of()"); \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler_types.h:451:74: note: expanded from macro '__same_type'
451 | #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
| ^
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
| ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
| ^~~~
include/linux/nfs_fs_sb.h:23:8: note: forward declaration of 'struct nfs41_impl_id'
23 | struct nfs41_impl_id;
| ^
>> fs/nfs/nfs4client.c:286:34: error: offsetof of incomplete type 'struct nfs41_impl_id'
286 | struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
| ^ ~~~~~~
include/linux/container_of.h:23:21: note: expanded from macro 'container_of'
23 | ((type *)(__mptr - offsetof(type, member))); })
| ^ ~~~~
include/linux/stddef.h:16:32: note: expanded from macro 'offsetof'
16 | #define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
| ^ ~~~~
include/linux/nfs_fs_sb.h:23:8: note: forward declaration of 'struct nfs41_impl_id'
23 | struct nfs41_impl_id;
| ^
>> fs/nfs/nfs4client.c:286:24: error: initializing 'struct nfs41_impl_id *' with an expression of incompatible type 'void'
286 | struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
| ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/nfs/nfs4client.c:304:27: error: incomplete definition of type 'struct nfs41_impl_id'
304 | call_rcu(&clp->cl_implid->__rcu_head, nfs4_free_impl_id_rcu);
| ~~~~~~~~~~~~~~^
include/linux/nfs_fs_sb.h:23:8: note: forward declaration of 'struct nfs41_impl_id'
23 | struct nfs41_impl_id;
| ^
4 errors generated.
Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for FB_IOMEM_HELPERS
Depends on [n]: HAS_IOMEM [=y] && FB_CORE [=n]
Selected by [m]:
- DRM_XE_DISPLAY [=y] && HAS_IOMEM [=y] && DRM [=y] && DRM_XE [=m] && DRM_XE [=m]=m [=m]
vim +286 fs/nfs/nfs4client.c
283
284 static void nfs4_free_impl_id_rcu(struct rcu_head *head)
285 {
> 286 struct nfs41_impl_id *impl_id = container_of(head, struct nfs41_impl_id, __rcu_head);
287
288 kfree(impl_id);
289 }
290
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
© 2016 - 2026 Red Hat, Inc.