Messages in this thread | | | Subject | Re: [PATCH 4.19,v2] VFS: Fix fuseblk memory leak caused by mount concurrency | From | "chenxiaosong (A)" <> | Date | Wed, 13 Oct 2021 18:38:12 +0800 |
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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@redhat.com/ >> >> Fixes: 79c0b2df79eb (add filesystem subtype support) >> Cc: David Howells <dhowells@redhat.com> >> Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com> >> --- >> 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.
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