[lvc-project] [PATCH v2] f2fs: ensure that node info flags are always initialized

Dmitry Antipov dmantipov at yandex.ru
Thu Dec 12 20:57:48 MSK 2024


Syzbot has reported the following KMSAN splat:

BUG: KMSAN: uninit-value in f2fs_new_node_page+0x1494/0x1630
 f2fs_new_node_page+0x1494/0x1630
 f2fs_new_inode_page+0xb9/0x100
 f2fs_init_inode_metadata+0x176/0x1e90
 f2fs_add_inline_entry+0x723/0xc90
 f2fs_do_add_link+0x48f/0xa70
 f2fs_symlink+0x6af/0xfc0
 vfs_symlink+0x1f1/0x470
 do_symlinkat+0x471/0xbc0
 __x64_sys_symlink+0xcf/0x140
 x64_sys_call+0x2fcc/0x3d90
 do_syscall_64+0xd9/0x1b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable new_ni created at:
 f2fs_new_node_page+0x9d/0x1630
 f2fs_new_inode_page+0xb9/0x100

So adjust 'f2fs_get_node_info()' to ensure that 'flag'
field of 'struct node_info' is always initialized.

Reported-by: syzbot+5141f6db57a2f7614352 at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5141f6db57a2f7614352
Fixes: e05df3b115e7 ("f2fs: add node operations")
Suggested-by: Chao Yu <chao at kernel.org>
Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
v2: move flag initialization to f2fs_get_node_info() as suggested by Chao
---
 fs/f2fs/node.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 0b900a7a48e5..c04ee1a7ce57 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -558,6 +558,7 @@ int f2fs_get_node_info(struct f2fs_sb_info *sbi, nid_t nid,
 	block_t blkaddr;
 	int i;
 
+	ni->flag = 0;
 	ni->nid = nid;
 retry:
 	/* Check nat cache */
-- 
2.47.1




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