[PATCH 5.19 117/717] f2fs: fix to do sanity check on summary info

Greg Kroah-Hartman
2022-10-22T08:10:52Z

From: Chao Yu <chao@kernel.org>

commit c6ad7fd16657ebd34a87a97d9588195aae87597d upstream.

As Wenqing Liu reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=216456

BUG: KASAN: use-after-free in recover_data+0x63ae/0x6ae0 [f2fs]
Read of size 4 at addr ffff8881464dcd80 by task mount/1013

CPU: 3 PID: 1013 Comm: mount Tainted: G W 6.0.0-rc4 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
Call Trace:
dump_stack_lvl+0x45/0x5e
print_report.cold+0xf3/0x68d
kasan_report+0xa8/0x130
recover_data+0x63ae/0x6ae0 [f2fs]
f2fs_recover_fsync_data+0x120d/0x1fc0 [f2fs]
f2fs_fill_super+0x4665/0x61e0 [f2fs]
mount_bdev+0x2cf/0x3b0
legacy_get_tree+0xed/0x1d0
vfs_get_tree+0x81/0x2b0
path_mount+0x47e/0x19d0
do_mount+0xce/0xf0
__x64_sys_mount+0x12c/0x1a0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is: in fuzzed image, SSA table is corrupted: ofs_in_node
is larger than ADDRS_PER_PAGE(), result in out-of-range access on 4k-size
page.

- recover_data
- do_recover_data
- check_index_in_prev_nodes
- f2fs_data_blkaddr

This patch adds sanity check on summary info in recovery and GC flow
in where the flows rely on them.

After patch:
[ 29.310883] F2FS-fs (loop0): Inconsistent ofs_in_node:65286 in summary, ino:0, nid:6, max:1018

Cc: stable@vger.kernel.org
Reported-by: Wenqing Liu <wenqingliu0120@gmail.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/gc.c | 10 +++++++++-
fs/f2fs/recovery.c | 15 ++++++++++++---
2 files changed, 21 insertions(+), 4 deletions(-)

--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -1075,7 +1075,7 @@ static bool is_alive(struct f2fs_sb_info
{
struct page *node_page;
nid_t nid;
- unsigned int ofs_in_node;
+ unsigned int ofs_in_node, max_addrs;
block_t source_blkaddr;

nid = le32_to_cpu(sum->nid);
@@ -1101,6 +1101,14 @@ static bool is_alive(struct f2fs_sb_info
return false;
}

+ max_addrs = IS_INODE(node_page) ? DEF_ADDRS_PER_INODE :
+ DEF_ADDRS_PER_BLOCK;
+ if (ofs_in_node >= max_addrs) {
+ f2fs_err(sbi, "Inconsistent ofs_in_node:%u in summary, ino:%u, nid:%u, max:%u",
+ ofs_in_node, dni->ino, dni->nid, max_addrs);
+ return false;
+ }
+
*nofs = ofs_of_node(node_page);
source_blkaddr = data_blkaddr(NULL, node_page, ofs_in_node);
f2fs_put_page(node_page, 1);
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -474,7 +474,7 @@ static int check_index_in_prev_nodes(str
struct dnode_of_data tdn = *dn;
nid_t ino, nid;
struct inode *inode;
- unsigned int offset;
+ unsigned int offset, ofs_in_node, max_addrs;
block_t bidx;
int i;

@@ -501,15 +501,24 @@ static int check_index_in_prev_nodes(str
got_it:
/* Use the locked dnode page and inode */
nid = le32_to_cpu(sum.nid);
+ ofs_in_node = le16_to_cpu(sum.ofs_in_node);
+
+ max_addrs = ADDRS_PER_PAGE(dn->node_page, dn->inode);
+ if (ofs_in_node >= max_addrs) {
+ f2fs_err(sbi, "Inconsistent ofs_in_node:%u in summary, ino:%lu, nid:%u, max:%u",
+ ofs_in_node, dn->inode->i_ino, nid, max_addrs);
+ return -EFSCORRUPTED;
+ }
+
if (dn->inode->i_ino == nid) {
tdn.nid = nid;
if (!dn->inode_page_locked)
lock_page(dn->inode_page);
tdn.node_page = dn->inode_page;
- tdn.ofs_in_node = le16_to_cpu(sum.ofs_in_node);
+ tdn.ofs_in_node = ofs_in_node;
goto truncate_out;
} else if (dn->nid == nid) {
- tdn.ofs_in_node = le16_to_cpu(sum.ofs_in_node);
+ tdn.ofs_in_node = ofs_in_node;
goto truncate_out;
}