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    Subject[PATCH 2/5] f2fs: avoid bug_on on corrupted inode
    Date
    syzbot has tested the proposed patch but the reproducer still triggered crash:
    kernel BUG at fs/f2fs/inode.c:LINE!

    F2FS-fs (loop1): invalid crc value
    F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0)
    F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock
    F2FS-fs (loop5): invalid crc value
    ------------[ cut here ]------------
    kernel BUG at fs/f2fs/inode.c:238!
    invalid opcode: 0000 [#1] SMP KASAN
    Dumping ftrace buffer:
    (ftrace buffer empty)
    Modules linked in:
    CPU: 1 PID: 4886 Comm: syz-executor1 Not tainted 4.17.0-rc1+ #1
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    RIP: 0010:do_read_inode fs/f2fs/inode.c:238 [inline]
    RIP: 0010:f2fs_iget+0x3307/0x3ca0 fs/f2fs/inode.c:313
    RSP: 0018:ffff8801c44a70e8 EFLAGS: 00010293
    RAX: ffff8801ce208040 RBX: ffff8801b3621080 RCX: ffffffff82eace18
    F2FS-fs (loop2): Magic Mismatch, valid(0xf2f52010) - read(0x0)
    RDX: 0000000000000000 RSI: ffffffff82eaf047 RDI: 0000000000000007
    RBP: ffff8801c44a7410 R08: ffff8801ce208040 R09: ffffed0039ee4176
    R10: ffffed0039ee4176 R11: ffff8801cf720bb7 R12: ffff8801c0efa000
    R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000000
    FS: 00007f753aa9d700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
    ------------[ cut here ]------------
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    kernel BUG at fs/f2fs/inode.c:238!
    CR2: 0000000001b03018 CR3: 00000001c8b74000 CR4: 00000000001406e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
    f2fs_fill_super+0x4377/0x7bf0 fs/f2fs/super.c:2842
    mount_bdev+0x30c/0x3e0 fs/super.c:1165
    f2fs_mount+0x34/0x40 fs/f2fs/super.c:3020
    mount_fs+0xae/0x328 fs/super.c:1268
    vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
    vfs_kern_mount fs/namespace.c:1027 [inline]
    do_new_mount fs/namespace.c:2517 [inline]
    do_mount+0x564/0x3070 fs/namespace.c:2847
    ksys_mount+0x12d/0x140 fs/namespace.c:3063
    __do_sys_mount fs/namespace.c:3077 [inline]
    __se_sys_mount fs/namespace.c:3074 [inline]
    __x64_sys_mount+0xbe/0x150 fs/namespace.c:3074
    do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x457daa
    RSP: 002b:00007f753aa9cba8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
    RAX: ffffffffffffffda RBX: 0000000020000000 RCX: 0000000000457daa
    RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f753aa9cbf0
    RBP: 0000000000000064 R08: 0000000020016a00 R09: 0000000020000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
    R13: 0000000000000064 R14: 00000000006fcb80 R15: 0000000000000000
    RIP: do_read_inode fs/f2fs/inode.c:238 [inline] RSP: ffff8801c44a70e8
    RIP: f2fs_iget+0x3307/0x3ca0 fs/f2fs/inode.c:313 RSP: ffff8801c44a70e8
    invalid opcode: 0000 [#2] SMP KASAN
    ---[ end trace 1cbcbec2156680bc ]---

    Reported-and-tested-by: syzbot+41a1b341571f0952badb@syzkaller.appspotmail.com
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    ---
    fs/f2fs/inode.c | 20 +++++++++++++++++++-
    1 file changed, 19 insertions(+), 1 deletion(-)

    diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
    index 414b1ede642b..7f2fe4574c48 100644
    --- a/fs/f2fs/inode.c
    +++ b/fs/f2fs/inode.c
    @@ -185,6 +185,21 @@ void f2fs_inode_chksum_set(struct f2fs_sb_info *sbi, struct page *page)
    ri->i_inode_checksum = cpu_to_le32(f2fs_inode_chksum(sbi, page));
    }

    +static bool sanity_check_inode(struct inode *inode)
    +{
    + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
    +
    + if (f2fs_sb_has_flexible_inline_xattr(sbi->sb)
    + && !f2fs_has_extra_attr(inode)) {
    + set_sbi_flag(sbi, SBI_NEED_FSCK);
    + f2fs_msg(sbi->sb, KERN_WARNING,
    + "%s: corrupted inode ino=%lx, run fsck to fix.",
    + __func__, inode->i_ino);
    + return false;
    + }
    + return true;
    +}
    +
    static int do_read_inode(struct inode *inode)
    {
    struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
    @@ -235,7 +250,6 @@ static int do_read_inode(struct inode *inode)
    le16_to_cpu(ri->i_extra_isize) : 0;

    if (f2fs_sb_has_flexible_inline_xattr(sbi->sb)) {
    - f2fs_bug_on(sbi, !f2fs_has_extra_attr(inode));
    fi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size);
    } else if (f2fs_has_inline_xattr(inode) ||
    f2fs_has_inline_dentry(inode)) {
    @@ -313,6 +327,10 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
    ret = do_read_inode(inode);
    if (ret)
    goto bad_inode;
    + if (!sanity_check_inode(inode)) {
    + ret = -EINVAL;
    + goto bad_inode;
    + }
    make_now:
    if (ino == F2FS_NODE_INO(sbi)) {
    inode->i_mapping->a_ops = &f2fs_node_aops;
    --
    2.17.0.484.g0c8726318c-goog
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