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    Subject[PATCH 5.3 074/112] cifs: use cifsInodeInfo->open_file_lock while iterating to avoid a panic
    Date
    From: Dave Wysochanski <dwysocha@redhat.com>

    commit cb248819d209d113e45fed459773991518e8e80b upstream.

    Commit 487317c99477 ("cifs: add spinlock for the openFileList to
    cifsInodeInfo") added cifsInodeInfo->open_file_lock spin_lock to protect
    the openFileList, but missed a few places where cifs_inode->openFileList
    was enumerated. Change these remaining tcon->open_file_lock to
    cifsInodeInfo->open_file_lock to avoid panic in is_size_safe_to_change.

    [17313.245641] RIP: 0010:is_size_safe_to_change+0x57/0xb0 [cifs]
    [17313.245645] Code: 68 40 48 89 ef e8 19 67 b7 f1 48 8b 43 40 48 8d 4b 40 48 8d 50 f0 48 39 c1 75 0f eb 47 48 8b 42 10 48 8d 50 f0 48 39 c1 74 3a <8b> 80 88 00 00 00 83 c0 01 a8 02 74 e6 48 89 ef c6 07 00 0f 1f 40
    [17313.245649] RSP: 0018:ffff94ae1baefa30 EFLAGS: 00010202
    [17313.245654] RAX: dead000000000100 RBX: ffff88dc72243300 RCX: ffff88dc72243340
    [17313.245657] RDX: dead0000000000f0 RSI: 00000000098f7940 RDI: ffff88dd3102f040
    [17313.245659] RBP: ffff88dd3102f040 R08: 0000000000000000 R09: ffff94ae1baefc40
    [17313.245661] R10: ffffcdc8bb1c4e80 R11: ffffcdc8b50adb08 R12: 00000000098f7940
    [17313.245663] R13: ffff88dc72243300 R14: ffff88dbc8f19600 R15: ffff88dc72243428
    [17313.245667] FS: 00007fb145485700(0000) GS:ffff88dd3e000000(0000) knlGS:0000000000000000
    [17313.245670] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [17313.245672] CR2: 0000026bb46c6000 CR3: 0000004edb110003 CR4: 00000000007606e0
    [17313.245753] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    [17313.245756] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    [17313.245759] PKRU: 55555554
    [17313.245761] Call Trace:
    [17313.245803] cifs_fattr_to_inode+0x16b/0x580 [cifs]
    [17313.245838] cifs_get_inode_info+0x35c/0xa60 [cifs]
    [17313.245852] ? kmem_cache_alloc_trace+0x151/0x1d0
    [17313.245885] cifs_open+0x38f/0x990 [cifs]
    [17313.245921] ? cifs_revalidate_dentry_attr+0x3e/0x350 [cifs]
    [17313.245953] ? cifsFileInfo_get+0x30/0x30 [cifs]
    [17313.245960] ? do_dentry_open+0x132/0x330
    [17313.245963] do_dentry_open+0x132/0x330
    [17313.245969] path_openat+0x573/0x14d0
    [17313.245974] do_filp_open+0x93/0x100
    [17313.245979] ? __check_object_size+0xa3/0x181
    [17313.245986] ? audit_alloc_name+0x7e/0xd0
    [17313.245992] do_sys_open+0x184/0x220
    [17313.245999] do_syscall_64+0x5b/0x1b0

    Fixes: 487317c99477 ("cifs: add spinlock for the openFileList to cifsInodeInfo")

    CC: Stable <stable@vger.kernel.org>
    Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
    Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
    Signed-off-by: Steve French <stfrench@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/cifs/file.c | 27 +++++++++++----------------
    1 file changed, 11 insertions(+), 16 deletions(-)

    --- a/fs/cifs/file.c
    +++ b/fs/cifs/file.c
    @@ -1853,13 +1853,12 @@ struct cifsFileInfo *find_readable_file(
    {
    struct cifsFileInfo *open_file = NULL;
    struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
    - struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);

    /* only filter by fsuid on multiuser mounts */
    if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
    fsuid_only = false;

    - spin_lock(&tcon->open_file_lock);
    + spin_lock(&cifs_inode->open_file_lock);
    /* we could simply get the first_list_entry since write-only entries
    are always at the end of the list but since the first entry might
    have a close pending, we go through the whole list */
    @@ -1871,7 +1870,7 @@ struct cifsFileInfo *find_readable_file(
    /* found a good file */
    /* lock it so it will not be closed on us */
    cifsFileInfo_get(open_file);
    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);
    return open_file;
    } /* else might as well continue, and look for
    another, or simply have the caller reopen it
    @@ -1879,7 +1878,7 @@ struct cifsFileInfo *find_readable_file(
    } else /* write only file */
    break; /* write only files are last so must be done */
    }
    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);
    return NULL;
    }

    @@ -1890,7 +1889,6 @@ cifs_get_writable_file(struct cifsInodeI
    {
    struct cifsFileInfo *open_file, *inv_file = NULL;
    struct cifs_sb_info *cifs_sb;
    - struct cifs_tcon *tcon;
    bool any_available = false;
    int rc = -EBADF;
    unsigned int refind = 0;
    @@ -1910,16 +1908,15 @@ cifs_get_writable_file(struct cifsInodeI
    }

    cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
    - tcon = cifs_sb_master_tcon(cifs_sb);

    /* only filter by fsuid on multiuser mounts */
    if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
    fsuid_only = false;

    - spin_lock(&tcon->open_file_lock);
    + spin_lock(&cifs_inode->open_file_lock);
    refind_writable:
    if (refind > MAX_REOPEN_ATT) {
    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);
    return rc;
    }
    list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
    @@ -1931,7 +1928,7 @@ refind_writable:
    if (!open_file->invalidHandle) {
    /* found a good writable file */
    cifsFileInfo_get(open_file);
    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);
    *ret_file = open_file;
    return 0;
    } else {
    @@ -1951,7 +1948,7 @@ refind_writable:
    cifsFileInfo_get(inv_file);
    }

    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);

    if (inv_file) {
    rc = cifs_reopen_file(inv_file, false);
    @@ -1966,7 +1963,7 @@ refind_writable:
    cifsFileInfo_put(inv_file);
    ++refind;
    inv_file = NULL;
    - spin_lock(&tcon->open_file_lock);
    + spin_lock(&cifs_inode->open_file_lock);
    goto refind_writable;
    }

    @@ -4405,17 +4402,15 @@ static int cifs_readpage(struct file *fi
    static int is_inode_writable(struct cifsInodeInfo *cifs_inode)
    {
    struct cifsFileInfo *open_file;
    - struct cifs_tcon *tcon =
    - cifs_sb_master_tcon(CIFS_SB(cifs_inode->vfs_inode.i_sb));

    - spin_lock(&tcon->open_file_lock);
    + spin_lock(&cifs_inode->open_file_lock);
    list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
    if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {
    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);
    return 1;
    }
    }
    - spin_unlock(&tcon->open_file_lock);
    + spin_unlock(&cifs_inode->open_file_lock);
    return 0;
    }


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