Revision 0ace17d56824165c7f4c68785d6b58971db954dd authored by Richard Palethorpe on 21 January 2020, 13:42:58 UTC, committed by David S. Miller on 22 January 2020, 19:32:03 UTC
write_wakeup can happen in parallel with close/hangup where tty->disc_data is set to NULL and the netdevice is freed thus also freeing disc_data. write_wakeup accesses disc_data so we must prevent close from freeing the netdev while write_wakeup has a non-NULL view of tty->disc_data. We also need to make sure that accesses to disc_data are atomic. Which can all be done with RCU. This problem was found by Syzkaller on SLCAN, but the same issue is reproducible with the SLIP line discipline using an LTP test based on the Syzkaller reproducer. A fix which didn't use RCU was posted by Hillf Danton. Fixes: 661f7fda21b1 ("slip: Fix deadlock in write_wakeup") Fixes: a8e83b17536a ("slcan: Port write_wakeup deadlock fix from slip") Reported-by: syzbot+017e491ae13c0068598a@syzkaller.appspotmail.com Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com> Cc: Wolfgang Grandegger <wg@grandegger.com> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Tyler Hall <tylerwhall@gmail.com> Cc: linux-can@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: syzkaller@googlegroups.com Signed-off-by: David S. Miller <davem@davemloft.net>
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inode.c
// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/hpfs/inode.c
*
* Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
*
* inode VFS functions
*/
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include "hpfs_fn.h"
void hpfs_init_inode(struct inode *i)
{
struct super_block *sb = i->i_sb;
struct hpfs_inode_info *hpfs_inode = hpfs_i(i);
i->i_uid = hpfs_sb(sb)->sb_uid;
i->i_gid = hpfs_sb(sb)->sb_gid;
i->i_mode = hpfs_sb(sb)->sb_mode;
i->i_size = -1;
i->i_blocks = -1;
hpfs_inode->i_dno = 0;
hpfs_inode->i_n_secs = 0;
hpfs_inode->i_file_sec = 0;
hpfs_inode->i_disk_sec = 0;
hpfs_inode->i_dpos = 0;
hpfs_inode->i_dsubdno = 0;
hpfs_inode->i_ea_mode = 0;
hpfs_inode->i_ea_uid = 0;
hpfs_inode->i_ea_gid = 0;
hpfs_inode->i_ea_size = 0;
hpfs_inode->i_rddir_off = NULL;
hpfs_inode->i_dirty = 0;
i->i_ctime.tv_sec = i->i_ctime.tv_nsec = 0;
i->i_mtime.tv_sec = i->i_mtime.tv_nsec = 0;
i->i_atime.tv_sec = i->i_atime.tv_nsec = 0;
}
void hpfs_read_inode(struct inode *i)
{
struct buffer_head *bh;
struct fnode *fnode;
struct super_block *sb = i->i_sb;
struct hpfs_inode_info *hpfs_inode = hpfs_i(i);
void *ea;
int ea_size;
if (!(fnode = hpfs_map_fnode(sb, i->i_ino, &bh))) {
/*i->i_mode |= S_IFREG;
i->i_mode &= ~0111;
i->i_op = &hpfs_file_iops;
i->i_fop = &hpfs_file_ops;
clear_nlink(i);*/
make_bad_inode(i);
return;
}
if (hpfs_sb(i->i_sb)->sb_eas) {
if ((ea = hpfs_get_ea(i->i_sb, fnode, "UID", &ea_size))) {
if (ea_size == 2) {
i_uid_write(i, le16_to_cpu(*(__le16*)ea));
hpfs_inode->i_ea_uid = 1;
}
kfree(ea);
}
if ((ea = hpfs_get_ea(i->i_sb, fnode, "GID", &ea_size))) {
if (ea_size == 2) {
i_gid_write(i, le16_to_cpu(*(__le16*)ea));
hpfs_inode->i_ea_gid = 1;
}
kfree(ea);
}
if ((ea = hpfs_get_ea(i->i_sb, fnode, "SYMLINK", &ea_size))) {
kfree(ea);
i->i_mode = S_IFLNK | 0777;
i->i_op = &page_symlink_inode_operations;
inode_nohighmem(i);
i->i_data.a_ops = &hpfs_symlink_aops;
set_nlink(i, 1);
i->i_size = ea_size;
i->i_blocks = 1;
brelse(bh);
return;
}
if ((ea = hpfs_get_ea(i->i_sb, fnode, "MODE", &ea_size))) {
int rdev = 0;
umode_t mode = hpfs_sb(sb)->sb_mode;
if (ea_size == 2) {
mode = le16_to_cpu(*(__le16*)ea);
hpfs_inode->i_ea_mode = 1;
}
kfree(ea);
i->i_mode = mode;
if (S_ISBLK(mode) || S_ISCHR(mode)) {
if ((ea = hpfs_get_ea(i->i_sb, fnode, "DEV", &ea_size))) {
if (ea_size == 4)
rdev = le32_to_cpu(*(__le32*)ea);
kfree(ea);
}
}
if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
brelse(bh);
set_nlink(i, 1);
i->i_size = 0;
i->i_blocks = 1;
init_special_inode(i, mode,
new_decode_dev(rdev));
return;
}
}
}
if (fnode_is_dir(fnode)) {
int n_dnodes, n_subdirs;
i->i_mode |= S_IFDIR;
i->i_op = &hpfs_dir_iops;
i->i_fop = &hpfs_dir_ops;
hpfs_inode->i_parent_dir = le32_to_cpu(fnode->up);
hpfs_inode->i_dno = le32_to_cpu(fnode->u.external[0].disk_secno);
if (hpfs_sb(sb)->sb_chk >= 2) {
struct buffer_head *bh0;
if (hpfs_map_fnode(sb, hpfs_inode->i_parent_dir, &bh0)) brelse(bh0);
}
n_dnodes = 0; n_subdirs = 0;
hpfs_count_dnodes(i->i_sb, hpfs_inode->i_dno, &n_dnodes, &n_subdirs, NULL);
i->i_blocks = 4 * n_dnodes;
i->i_size = 2048 * n_dnodes;
set_nlink(i, 2 + n_subdirs);
} else {
i->i_mode |= S_IFREG;
if (!hpfs_inode->i_ea_mode) i->i_mode &= ~0111;
i->i_op = &hpfs_file_iops;
i->i_fop = &hpfs_file_ops;
set_nlink(i, 1);
i->i_size = le32_to_cpu(fnode->file_size);
i->i_blocks = ((i->i_size + 511) >> 9) + 1;
i->i_data.a_ops = &hpfs_aops;
hpfs_i(i)->mmu_private = i->i_size;
}
brelse(bh);
}
static void hpfs_write_inode_ea(struct inode *i, struct fnode *fnode)
{
struct hpfs_inode_info *hpfs_inode = hpfs_i(i);
/*if (le32_to_cpu(fnode->acl_size_l) || le16_to_cpu(fnode->acl_size_s)) {
Some unknown structures like ACL may be in fnode,
we'd better not overwrite them
hpfs_error(i->i_sb, "fnode %08x has some unknown HPFS386 structures", i->i_ino);
} else*/ if (hpfs_sb(i->i_sb)->sb_eas >= 2) {
__le32 ea;
if (!uid_eq(i->i_uid, hpfs_sb(i->i_sb)->sb_uid) || hpfs_inode->i_ea_uid) {
ea = cpu_to_le32(i_uid_read(i));
hpfs_set_ea(i, fnode, "UID", (char*)&ea, 2);
hpfs_inode->i_ea_uid = 1;
}
if (!gid_eq(i->i_gid, hpfs_sb(i->i_sb)->sb_gid) || hpfs_inode->i_ea_gid) {
ea = cpu_to_le32(i_gid_read(i));
hpfs_set_ea(i, fnode, "GID", (char *)&ea, 2);
hpfs_inode->i_ea_gid = 1;
}
if (!S_ISLNK(i->i_mode))
if ((i->i_mode != ((hpfs_sb(i->i_sb)->sb_mode & ~(S_ISDIR(i->i_mode) ? 0 : 0111))
| (S_ISDIR(i->i_mode) ? S_IFDIR : S_IFREG))
&& i->i_mode != ((hpfs_sb(i->i_sb)->sb_mode & ~(S_ISDIR(i->i_mode) ? 0222 : 0333))
| (S_ISDIR(i->i_mode) ? S_IFDIR : S_IFREG))) || hpfs_inode->i_ea_mode) {
ea = cpu_to_le32(i->i_mode);
/* sick, but legal */
hpfs_set_ea(i, fnode, "MODE", (char *)&ea, 2);
hpfs_inode->i_ea_mode = 1;
}
if (S_ISBLK(i->i_mode) || S_ISCHR(i->i_mode)) {
ea = cpu_to_le32(new_encode_dev(i->i_rdev));
hpfs_set_ea(i, fnode, "DEV", (char *)&ea, 4);
}
}
}
void hpfs_write_inode(struct inode *i)
{
struct hpfs_inode_info *hpfs_inode = hpfs_i(i);
struct inode *parent;
if (i->i_ino == hpfs_sb(i->i_sb)->sb_root) return;
if (hpfs_inode->i_rddir_off && !atomic_read(&i->i_count)) {
if (*hpfs_inode->i_rddir_off)
pr_err("write_inode: some position still there\n");
kfree(hpfs_inode->i_rddir_off);
hpfs_inode->i_rddir_off = NULL;
}
if (!i->i_nlink) {
return;
}
parent = iget_locked(i->i_sb, hpfs_inode->i_parent_dir);
if (parent) {
hpfs_inode->i_dirty = 0;
if (parent->i_state & I_NEW) {
hpfs_init_inode(parent);
hpfs_read_inode(parent);
unlock_new_inode(parent);
}
hpfs_write_inode_nolock(i);
iput(parent);
}
}
void hpfs_write_inode_nolock(struct inode *i)
{
struct hpfs_inode_info *hpfs_inode = hpfs_i(i);
struct buffer_head *bh;
struct fnode *fnode;
struct quad_buffer_head qbh;
struct hpfs_dirent *de;
if (i->i_ino == hpfs_sb(i->i_sb)->sb_root) return;
if (!(fnode = hpfs_map_fnode(i->i_sb, i->i_ino, &bh))) return;
if (i->i_ino != hpfs_sb(i->i_sb)->sb_root && i->i_nlink) {
if (!(de = map_fnode_dirent(i->i_sb, i->i_ino, fnode, &qbh))) {
brelse(bh);
return;
}
} else de = NULL;
if (S_ISREG(i->i_mode)) {
fnode->file_size = cpu_to_le32(i->i_size);
if (de) de->file_size = cpu_to_le32(i->i_size);
} else if (S_ISDIR(i->i_mode)) {
fnode->file_size = cpu_to_le32(0);
if (de) de->file_size = cpu_to_le32(0);
}
hpfs_write_inode_ea(i, fnode);
if (de) {
de->write_date = cpu_to_le32(gmt_to_local(i->i_sb, i->i_mtime.tv_sec));
de->read_date = cpu_to_le32(gmt_to_local(i->i_sb, i->i_atime.tv_sec));
de->creation_date = cpu_to_le32(gmt_to_local(i->i_sb, i->i_ctime.tv_sec));
de->read_only = !(i->i_mode & 0222);
de->ea_size = cpu_to_le32(hpfs_inode->i_ea_size);
hpfs_mark_4buffers_dirty(&qbh);
hpfs_brelse4(&qbh);
}
if (S_ISDIR(i->i_mode)) {
if ((de = map_dirent(i, hpfs_inode->i_dno, "\001\001", 2, NULL, &qbh))) {
de->write_date = cpu_to_le32(gmt_to_local(i->i_sb, i->i_mtime.tv_sec));
de->read_date = cpu_to_le32(gmt_to_local(i->i_sb, i->i_atime.tv_sec));
de->creation_date = cpu_to_le32(gmt_to_local(i->i_sb, i->i_ctime.tv_sec));
de->read_only = !(i->i_mode & 0222);
de->ea_size = cpu_to_le32(/*hpfs_inode->i_ea_size*/0);
de->file_size = cpu_to_le32(0);
hpfs_mark_4buffers_dirty(&qbh);
hpfs_brelse4(&qbh);
} else
hpfs_error(i->i_sb,
"directory %08lx doesn't have '.' entry",
(unsigned long)i->i_ino);
}
mark_buffer_dirty(bh);
brelse(bh);
}
int hpfs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
int error = -EINVAL;
hpfs_lock(inode->i_sb);
if (inode->i_ino == hpfs_sb(inode->i_sb)->sb_root)
goto out_unlock;
if ((attr->ia_valid & ATTR_UID) &&
from_kuid(&init_user_ns, attr->ia_uid) >= 0x10000)
goto out_unlock;
if ((attr->ia_valid & ATTR_GID) &&
from_kgid(&init_user_ns, attr->ia_gid) >= 0x10000)
goto out_unlock;
if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size > inode->i_size)
goto out_unlock;
error = setattr_prepare(dentry, attr);
if (error)
goto out_unlock;
if ((attr->ia_valid & ATTR_SIZE) &&
attr->ia_size != i_size_read(inode)) {
error = inode_newsize_ok(inode, attr->ia_size);
if (error)
goto out_unlock;
truncate_setsize(inode, attr->ia_size);
hpfs_truncate(inode);
}
setattr_copy(inode, attr);
hpfs_write_inode(inode);
out_unlock:
hpfs_unlock(inode->i_sb);
return error;
}
void hpfs_write_if_changed(struct inode *inode)
{
struct hpfs_inode_info *hpfs_inode = hpfs_i(inode);
if (hpfs_inode->i_dirty)
hpfs_write_inode(inode);
}
void hpfs_evict_inode(struct inode *inode)
{
truncate_inode_pages_final(&inode->i_data);
clear_inode(inode);
if (!inode->i_nlink) {
hpfs_lock(inode->i_sb);
hpfs_remove_fnode(inode->i_sb, inode->i_ino);
hpfs_unlock(inode->i_sb);
}
}
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