diff options
| author | Gao Xiang <hsiangkao@linux.alibaba.com> | 2025-11-22 14:23:32 +0800 |
|---|---|---|
| committer | Gao Xiang <hsiangkao@linux.alibaba.com> | 2025-11-24 14:17:29 +0800 |
| commit | d53cd891f0e4311889349fff3a784dc552f814b9 (patch) | |
| tree | 9fae614c62906630405f2193cfa52793028b9246 | |
| parent | ebe4f3f6eb0c10f87c58e52a8912694c14fdeda6 (diff) | |
erofs: limit the level of fs stacking for file-backed mounts
Otherwise, it could cause potential kernel stack overflow (e.g., EROFS
mounting itself).
Reviewed-by: Sheng Yong <shengyong1@xiaomi.com>
Fixes: fb176750266a ("erofs: add file-backed mount support")
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
| -rw-r--r-- | fs/erofs/super.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/fs/erofs/super.c b/fs/erofs/super.c index cd8ff98c2938..937a215f626c 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -639,6 +639,22 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc) sbi->blkszbits = PAGE_SHIFT; if (!sb->s_bdev) { + /* + * (File-backed mounts) EROFS claims it's safe to nest other + * fs contexts (including its own) due to self-controlled RO + * accesses/contexts and no side-effect changes that need to + * context save & restore so it can reuse the current thread + * context. However, it still needs to bump `s_stack_depth` to + * avoid kernel stack overflow from nested filesystems. + */ + if (erofs_is_fileio_mode(sbi)) { + sb->s_stack_depth = + file_inode(sbi->dif0.file)->i_sb->s_stack_depth + 1; + if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { + erofs_err(sb, "maximum fs stacking depth exceeded"); + return -ENOTBLK; + } + } sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; |