From: Ryusuke Konishi <konishi.ryusuke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
syzbot
<syzbot+132fdd2f1e1805fdc591-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org>,
syzkaller-bugs-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
glider-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org
Subject: [PATCH] nilfs2: fix kernel-infoleak in nilfs_ioctl_wrap_copy()
Date: Tue, 7 Mar 2023 17:55:48 +0900 [thread overview]
Message-ID: <20230307085548.6290-1-konishi.ryusuke@gmail.com> (raw)
In-Reply-To: <000000000000a5bd2d05f63f04ae-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
The ioctl helper function nilfs_ioctl_wrap_copy, which exchanges a
metadata array to/from user space, may copy uninitialized buffer regions
to user space memory for read-only ioctl commands NILFS_IOCTL_GET_SUINFO
and NILFS_IOCTL_GET_CPINFO.
This can occur when the element size of the user space metadata given
by the v_size member of the argument nilfs_argv structure is larger than
the size of the metadata element (nilfs_suinfo structure or nilfs_cpinfo
structure) on the file system side.
KMSAN-enabled kernels detect this issue as follows:
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user
include/linux/instrumented.h:121 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_user+0xc0/0x100 lib/usercopy.c:33
instrument_copy_to_user include/linux/instrumented.h:121 [inline]
_copy_to_user+0xc0/0x100 lib/usercopy.c:33
copy_to_user include/linux/uaccess.h:169 [inline]
nilfs_ioctl_wrap_copy+0x6fa/0xc10 fs/nilfs2/ioctl.c:99
nilfs_ioctl_get_info fs/nilfs2/ioctl.c:1173 [inline]
nilfs_ioctl+0x2402/0x4450 fs/nilfs2/ioctl.c:1290
nilfs_compat_ioctl+0x1b8/0x200 fs/nilfs2/ioctl.c:1343
__do_compat_sys_ioctl fs/ioctl.c:968 [inline]
__se_compat_sys_ioctl+0x7dd/0x1000 fs/ioctl.c:910
__ia32_compat_sys_ioctl+0x93/0xd0 fs/ioctl.c:910
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
do_fast_syscall_32+0x37/0x80 arch/x86/entry/common.c:203
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:246
entry_SYSENTER_compat_after_hwframe+0x70/0x82
Uninit was created at:
__alloc_pages+0x9f6/0xe90 mm/page_alloc.c:5572
alloc_pages+0xab0/0xd80 mm/mempolicy.c:2287
__get_free_pages+0x34/0xc0 mm/page_alloc.c:5599
nilfs_ioctl_wrap_copy+0x223/0xc10 fs/nilfs2/ioctl.c:74
nilfs_ioctl_get_info fs/nilfs2/ioctl.c:1173 [inline]
nilfs_ioctl+0x2402/0x4450 fs/nilfs2/ioctl.c:1290
nilfs_compat_ioctl+0x1b8/0x200 fs/nilfs2/ioctl.c:1343
__do_compat_sys_ioctl fs/ioctl.c:968 [inline]
__se_compat_sys_ioctl+0x7dd/0x1000 fs/ioctl.c:910
__ia32_compat_sys_ioctl+0x93/0xd0 fs/ioctl.c:910
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
do_fast_syscall_32+0x37/0x80 arch/x86/entry/common.c:203
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:246
entry_SYSENTER_compat_after_hwframe+0x70/0x82
Bytes 16-127 of 3968 are uninitialized
...
This eliminates the leak issue by initializing the page allocated as
buffer using get_zeroed_page().
Signed-off-by: Ryusuke Konishi <konishi.ryusuke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Reported-by: syzbot+132fdd2f1e1805fdc591-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org
Link: https://lkml.kernel.org/r/000000000000a5bd2d05f63f04ae-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org
Tested-by: Ryusuke Konishi <konishi.ryusuke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
fs/nilfs2/ioctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 5ccc638ae92f..1dfbc0c34513 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -71,7 +71,7 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
if (argv->v_index > ~(__u64)0 - argv->v_nmembs)
return -EINVAL;
- buf = (void *)__get_free_pages(GFP_NOFS, 0);
+ buf = (void *)get_zeroed_page(GFP_NOFS);
if (unlikely(!buf))
return -ENOMEM;
maxmembs = PAGE_SIZE / argv->v_size;
--
2.34.1
prev parent reply other threads:[~2023-03-07 8:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 17:56 [syzbot] [nilfs?] KMSAN: kernel-infoleak in nilfs_ioctl_wrap_copy syzbot
[not found] ` <000000000000a5bd2d05f63f04ae-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2023-03-07 8:55 ` Ryusuke Konishi [this message]
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