Commit 4099a510 authored by Jorge Mora's avatar Jorge Mora Committed by Long Li
Browse files

NFSv4.2: fix nfs4_listxattr kernel BUG at mm/usercopy.c:102 

stable inclusion
from stable-v5.10.167
commit 4403438eaca6e91f02d272211c4d6b045092396b
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9HK78
CVE: CVE-2024-26870

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=4403438eaca6e91f02d272211c4d6b045092396b



--------------------------------

[ Upstream commit 251a658bbfceafb4d58c76b77682c8bf7bcfad65 ]

A call to listxattr() with a buffer size = 0 returns the actual
size of the buffer needed for a subsequent call. When size > 0,
nfs4_listxattr() does not return an error because either
generic_listxattr() or nfs4_listxattr_nfs4_label() consumes
exactly all the bytes then size is 0 when calling
nfs4_listxattr_nfs4_user() which then triggers the following
kernel BUG:

  [   99.403778] kernel BUG at mm/usercopy.c:102!
  [   99.404063] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
  [   99.408463] CPU: 0 PID: 3310 Comm: python3 Not tainted 6.6.0-61.fc40.aarch64 #1
  [   99.415827] Call trace:
  [   99.415985]  usercopy_abort+0x70/0xa0
  [   99.416227]  __check_heap_object+0x134/0x158
  [   99.416505]  check_heap_object+0x150/0x188
  [   99.416696]  __check_object_size.part.0+0x78/0x168
  [   99.416886]  __check_object_size+0x28/0x40
  [   99.417078]  listxattr+0x8c/0x120
  [   99.417252]  path_listxattr+0x78/0xe0
  [   99.417476]  __arm64_sys_listxattr+0x28/0x40
  [   99.417723]  invoke_syscall+0x78/0x100
  [   99.417929]  el0_svc_common.constprop.0+0x48/0xf0
  [   99.418186]  do_el0_svc+0x24/0x38
  [   99.418376]  el0_svc+0x3c/0x110
  [   99.418554]  el0t_64_sync_handler+0x120/0x130
  [   99.418788]  el0t_64_sync+0x194/0x198
  [   99.418994] Code: aa0003e3 d000a3e0 91310000 97f49bdb (d4210000)

Issue is reproduced when generic_listxattr() returns 'system.nfs4_acl',
thus calling lisxattr() with size = 16 will trigger the bug.

Add check on nfs4_listxattr() to return ERANGE error when it is
called with size > 0 and the return value is greater than size.

Fixes: 012a211a ("NFSv4.2: hook in the user extended attribute handlers")
Signed-off-by: default avatarJorge Mora <mora@netapp.com>
Reviewed-by: default avatarBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarLong Li <leo.lilong@huawei.com>
parent a37954d8

fs/nfs/nfs4proc.c

+10 −6
Original line number Diff line number Diff line
@@ -10367,29 +10367,33 @@ const struct nfs4_minor_version_ops *nfs_v4_minor_ops[] = { 
static ssize_t nfs4_listxattr(struct dentry *dentry, char *list, size_t size)

{

	ssize_t error, error2, error3;

	size_t left = size;



	error = generic_listxattr(dentry, list, size);

	error = generic_listxattr(dentry, list, left);

	if (error < 0)

		return error;

	if (list) {

		list += error;

		size -= error;

		left -= error;

	}



	error2 = nfs4_listxattr_nfs4_label(d_inode(dentry), list, size);

	error2 = nfs4_listxattr_nfs4_label(d_inode(dentry), list, left);

	if (error2 < 0)

		return error2;



	if (list) {

		list += error2;

		size -= error2;

		left -= error2;

	}



	error3 = nfs4_listxattr_nfs4_user(d_inode(dentry), list, size);

	error3 = nfs4_listxattr_nfs4_user(d_inode(dentry), list, left);

	if (error3 < 0)

		return error3;



	return error + error2 + error3;

	error += error2 + error3;

	if (size && error > size)

		return -ERANGE;

	return error;

}



static void nfs4_enable_swap(struct inode *inode)