[PATCH 6.1 109/127] f2fs: fix to do sanity check on direct node in truncate_dnode()

Greg Kroah-Hartman
2023-08-09T10:56:15Z

From: Chao Yu <chao@kernel.org>

commit a6ec83786ab9f13f25fb18166dee908845713a95 upstream.

syzbot reports below bug:

BUG: KASAN: slab-use-after-free in f2fs_truncate_data_blocks_range+0x122a/0x14c0 fs/f2fs/file.c:574
Read of size 4 at addr ffff88802a25c000 by task syz-executor148/5000

CPU: 1 PID: 5000 Comm: syz-executor148 Not tainted 6.4.0-rc7-syzkaller-00041-ge660abd551f1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
print_report mm/kasan/report.c:462 [inline]
kasan_report+0x11c/0x130 mm/kasan/report.c:572
f2fs_truncate_data_blocks_range+0x122a/0x14c0 fs/f2fs/file.c:574
truncate_dnode+0x229/0x2e0 fs/f2fs/node.c:944
f2fs_truncate_inode_blocks+0x64b/0xde0 fs/f2fs/node.c:1154
f2fs_do_truncate_blocks+0x4ac/0xf30 fs/f2fs/file.c:721
f2fs_truncate_blocks+0x7b/0x300 fs/f2fs/file.c:749
f2fs_truncate.part.0+0x4a5/0x630 fs/f2fs/file.c:799
f2fs_truncate include/linux/fs.h:825 [inline]
f2fs_setattr+0x1738/0x2090 fs/f2fs/file.c:1006
notify_change+0xb2c/0x1180 fs/attr.c:483
do_truncate+0x143/0x200 fs/open.c:66
handle_truncate fs/namei.c:3295 [inline]
do_open fs/namei.c:3640 [inline]
path_openat+0x2083/0x2750 fs/namei.c:3791
do_filp_open+0x1ba/0x410 fs/namei.c:3818
do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_creat fs/open.c:1448 [inline]
__se_sys_creat fs/open.c:1442 [inline]
__x64_sys_creat+0xcd/0x120 fs/open.c:1442
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is, inodeA references inodeB via inodeB's ino, once inodeA
is truncated, it calls truncate_dnode() to truncate data blocks in inodeB's
node page, it traverse mapping data from node->i.i_addr[0] to
node->i.i_addr[ADDRS_PER_BLOCK() - 1], result in out-of-boundary access.

This patch fixes to add sanity check on dnode page in truncate_dnode(),
so that, it can help to avoid triggering such issue, and once it encounters
such issue, it will record newly introduced ERROR_INVALID_NODE_REFERENCE
error into superblock, later fsck can detect such issue and try repairing.

Also, it removes f2fs_truncate_data_blocks() for cleanup due to the
function has only one caller, and uses f2fs_truncate_data_blocks_range()
instead.

Reported-and-tested-by: syzbot+12cb4425b22169b52036@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-f2fs-devel/000000000000f3038a05fef867f8@google.com
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/f2fs/f2fs.h | 1 -
fs/f2fs/file.c | 5 -----
fs/f2fs/node.c | 14 ++++++++++++--
include/linux/f2fs_fs.h | 1 +
4 files changed, 13 insertions(+), 8 deletions(-)

--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3431,7 +3431,6 @@ static inline bool __is_valid_data_blkad
* file.c
*/
int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync);
-void f2fs_truncate_data_blocks(struct dnode_of_data *dn);
int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock);
int f2fs_truncate_blocks(struct inode *inode, u64 from, bool lock);
int f2fs_truncate(struct inode *inode);
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -628,11 +628,6 @@ void f2fs_truncate_data_blocks_range(str
dn->ofs_in_node, nr_free);
}

-void f2fs_truncate_data_blocks(struct dnode_of_data *dn)
-{
- f2fs_truncate_data_blocks_range(dn, ADDRS_PER_BLOCK(dn->inode));
-}
-
static int truncate_partial_data_page(struct inode *inode, u64 from,
bool cache_only)
{
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -923,6 +923,7 @@ static int truncate_node(struct dnode_of

static int truncate_dnode(struct dnode_of_data *dn)
{
+ struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
struct page *page;
int err;

@@ -930,16 +931,25 @@ static int truncate_dnode(struct dnode_o
return 1;

/* get direct node */
- page = f2fs_get_node_page(F2FS_I_SB(dn->inode), dn->nid);
+ page = f2fs_get_node_page(sbi, dn->nid);
if (PTR_ERR(page) == -ENOENT)
return 1;
else if (IS_ERR(page))
return PTR_ERR(page);

+ if (IS_INODE(page) || ino_of_node(page) != dn->inode->i_ino) {
+ f2fs_err(sbi, "incorrect node reference, ino: %lu, nid: %u, ino_of_node: %u",
+ dn->inode->i_ino, dn->nid, ino_of_node(page));
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ f2fs_handle_error(sbi, ERROR_INVALID_NODE_REFERENCE);
+ f2fs_put_page(page, 1);
+ return -EFSCORRUPTED;
+ }
+
/* Make dnode_of_data for parameter */
dn->node_page = page;
dn->ofs_in_node = 0;
- f2fs_truncate_data_blocks(dn);
+ f2fs_truncate_data_blocks_range(dn, ADDRS_PER_BLOCK(dn->inode));
err = truncate_node(dn);
if (err) {
f2fs_put_page(page, 1);
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -104,6 +104,7 @@ enum f2fs_error {
ERROR_INCONSISTENT_SIT,
ERROR_CORRUPTED_VERITY_XATTR,
ERROR_CORRUPTED_XATTR,
+ ERROR_INVALID_NODE_REFERENCE,
ERROR_MAX,
};