在 2021/10/13 18:38, chenxiaosong (A) 写道:
在 2021/10/13 18:11, Greg KH 写道:
On Wed, Oct 13, 2021 at 05:51:01PM +0800, ChenXiaoSong wrote:
If two processes mount same superblock, memory leak occurs:
CPU0 | CPU1
do_new_mount | do_new_mount
fs_set_subtype | fs_set_subtype
kstrdup |
| kstrdup
memrory leak |
Fix this by adding a write lock while calling fs_set_subtype.
Linus's tree already have refactoring patchset [1], one of them can
fix this bug:
c30da2e981a7 (fuse: convert to use the new mount API)
Since we did not merge the refactoring patchset in this branch, I
create this patch.
[1]
https://patchwork.kernel.org/project/linux-fsdevel/patch/20190903113640.7984-3-mszeredi@xxxxxxxxxx/
Fixes: 79c0b2df79eb (add filesystem subtype support)
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: ChenXiaoSong <chenxiaosong2@xxxxxxxxxx>
---
v1: Can not mount sshfs ([PATCH linux-4.19.y] VFS: Fix fuseblk memory
leak caused by mount concurrency)
v2: Use write lock while writing superblock
fs/namespace.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
As you are referring to a fuse-only patch above, why are you trying to
resolve this issue in the core namespace code instead?
How does fuse have anything to do with this?
confused,
greg k-h
.
Now, only `fuse_fs_type` and `fuseblk_fs_type` has `FS_HAS_SUBTYPE` flag
in kernel code, but maybe there is a filesystem module(`struct
file_system_type` has `FS_HAS_SUBTYPE` flag). And only mounting fuseblk
filesystem(e.g. ntfs) will occur memory leak now.
How about updating the subject as: VFS: Fix memory leak caused by
mounting fs with subtype concurrency?
