Commit a6ec8378 authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: fix to do sanity check on direct node in truncate_dnode() 



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: default avatar <syzbot+12cb4425b22169b52036@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/linux-f2fs-devel/000000000000f3038a05fef867f8@google.com


Signed-off-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 87a91a15

fs/f2fs/f2fs.h

+0 −1
Original line number Diff line number Diff line
@@ -3457,7 +3457,6 @@ static inline bool __is_valid_data_blkaddr(block_t blkaddr) 
 * 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);

fs/f2fs/file.c

+0 −5
Original line number Diff line number Diff line
@@ -626,11 +626,6 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count) 
					 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)

{

fs/f2fs/node.c

+12 −2
Original line number Diff line number Diff line
@@ -925,6 +925,7 @@ static int truncate_node(struct dnode_of_data *dn) 


static int truncate_dnode(struct dnode_of_data *dn)

{

	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);

	struct page *page;

	int err;
@@ -932,16 +933,25 @@ static int truncate_dnode(struct dnode_of_data *dn) 
		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);

include/linux/f2fs_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ enum f2fs_error { 
	ERROR_INCONSISTENT_SIT,

	ERROR_CORRUPTED_VERITY_XATTR,

	ERROR_CORRUPTED_XATTR,

	ERROR_INVALID_NODE_REFERENCE,

	ERROR_MAX,

};