From 416a8b2c02fe2a5a9fbdf2a35ea294b78d939f84 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Tue, 17 Sep 2024 21:08:03 +0800 Subject: [PATCH] erofs: ensure regular inodes for file-backed mounts Only regular inodes are allowed for file-backed mounts, not directories (as seen in the original syzbot case) or special inodes. Also ensure that .read_folio() is implemented on the underlying fs for the primary device. Fixes: fb176750266a ("erofs: add file-backed mount support") Reported-by: syzbot+001306cd9c92ce0df23f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/00000000000011bdde0622498ee3@google.com Tested-by: syzbot+001306cd9c92ce0df23f@syzkaller.appspotmail.com Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20240917130803.32418-1-hsiangkao@linux.alibaba.com --- fs/erofs/super.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/erofs/super.c b/fs/erofs/super.c index 666873f745da..320d586c3896 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -191,10 +191,14 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb, if (IS_ERR(file)) return PTR_ERR(file); - dif->file = file; - if (!erofs_is_fileio_mode(sbi)) + if (!erofs_is_fileio_mode(sbi)) { dif->dax_dev = fs_dax_get_by_bdev(file_bdev(file), &dif->dax_part_off, NULL, NULL); + } else if (!S_ISREG(file_inode(file)->i_mode)) { + fput(file); + return -EINVAL; + } + dif->file = file; } dif->blocks = le32_to_cpu(dis->blocks); @@ -714,7 +718,10 @@ static int erofs_fc_get_tree(struct fs_context *fc) if (IS_ERR(sbi->fdev)) return PTR_ERR(sbi->fdev); - return get_tree_nodev(fc, erofs_fc_fill_super); + if (S_ISREG(file_inode(sbi->fdev)->i_mode) && + sbi->fdev->f_mapping->a_ops->read_folio) + return get_tree_nodev(fc, erofs_fc_fill_super); + fput(sbi->fdev); } #endif return ret;