kernel-ark/fs/autofs/waitq.c
Ian Kent ba8df43c0e [PATCH] autofs4: panic after mount fail
Resolve the panic on failed mount of an autofs filesystem originally
reported by Mao Bibo.

It addresses two issues that happen after the mount fail.  The first a NULL
pointer reference to a field (pipe) in the autofs superblock info structure
and second the lack of super block cleanup by the autofs and autofs4
modules.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-14 09:09:27 -08:00

206 lines
5.3 KiB
C

/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/autofs/waitq.c
*
* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/signal.h>
#include <linux/file.h>
#include "autofs_i.h"
/* We make this a static variable rather than a part of the superblock; it
is better if we don't reassign numbers easily even across filesystems */
static autofs_wqt_t autofs_next_wait_queue = 1;
/* These are the signals we allow interrupting a pending mount */
#define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
void autofs_catatonic_mode(struct autofs_sb_info *sbi)
{
struct autofs_wait_queue *wq, *nwq;
DPRINTK(("autofs: entering catatonic mode\n"));
sbi->catatonic = 1;
wq = sbi->queues;
sbi->queues = NULL; /* Erase all wait queues */
while ( wq ) {
nwq = wq->next;
wq->status = -ENOENT; /* Magic is gone - report failure */
kfree(wq->name);
wq->name = NULL;
wake_up(&wq->queue);
wq = nwq;
}
fput(sbi->pipe); /* Close the pipe */
sbi->pipe = NULL;
autofs_hash_dputall(&sbi->dirhash); /* Remove all dentry pointers */
}
static int autofs_write(struct file *file, const void *addr, int bytes)
{
unsigned long sigpipe, flags;
mm_segment_t fs;
const char *data = (const char *)addr;
ssize_t wr = 0;
/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
sigpipe = sigismember(&current->pending.signal, SIGPIPE);
/* Save pointer to user space and point back to kernel space */
fs = get_fs();
set_fs(KERNEL_DS);
while (bytes &&
(wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
data += wr;
bytes -= wr;
}
set_fs(fs);
/* Keep the currently executing process from receiving a
SIGPIPE unless it was already supposed to get one */
if (wr == -EPIPE && !sigpipe) {
spin_lock_irqsave(&current->sighand->siglock, flags);
sigdelset(&current->pending.signal, SIGPIPE);
recalc_sigpending();
spin_unlock_irqrestore(&current->sighand->siglock, flags);
}
return (bytes > 0);
}
static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq)
{
struct autofs_packet_missing pkt;
DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token));
autofs_say(wq->name,wq->len);
memset(&pkt,0,sizeof pkt); /* For security reasons */
pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
pkt.hdr.type = autofs_ptype_missing;
pkt.wait_queue_token = wq->wait_queue_token;
pkt.len = wq->len;
memcpy(pkt.name, wq->name, pkt.len);
pkt.name[pkt.len] = '\0';
if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) )
autofs_catatonic_mode(sbi);
}
int autofs_wait(struct autofs_sb_info *sbi, struct qstr *name)
{
struct autofs_wait_queue *wq;
int status;
/* In catatonic mode, we don't wait for nobody */
if ( sbi->catatonic )
return -ENOENT;
/* We shouldn't be able to get here, but just in case */
if ( name->len > NAME_MAX )
return -ENOENT;
for ( wq = sbi->queues ; wq ; wq = wq->next ) {
if ( wq->hash == name->hash &&
wq->len == name->len &&
wq->name && !memcmp(wq->name,name->name,name->len) )
break;
}
if ( !wq ) {
/* Create a new wait queue */
wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
if ( !wq )
return -ENOMEM;
wq->name = kmalloc(name->len,GFP_KERNEL);
if ( !wq->name ) {
kfree(wq);
return -ENOMEM;
}
wq->wait_queue_token = autofs_next_wait_queue++;
init_waitqueue_head(&wq->queue);
wq->hash = name->hash;
wq->len = name->len;
wq->status = -EINTR; /* Status return if interrupted */
memcpy(wq->name, name->name, name->len);
wq->next = sbi->queues;
sbi->queues = wq;
/* autofs_notify_daemon() may block */
wq->wait_ctr = 2;
autofs_notify_daemon(sbi,wq);
} else
wq->wait_ctr++;
/* wq->name is NULL if and only if the lock is already released */
if ( sbi->catatonic ) {
/* We might have slept, so check again for catatonic mode */
wq->status = -ENOENT;
kfree(wq->name);
wq->name = NULL;
}
if ( wq->name ) {
/* Block all but "shutdown" signals while waiting */
sigset_t sigmask;
siginitsetinv(&sigmask, SHUTDOWN_SIGS);
sigprocmask(SIG_BLOCK, &sigmask, &sigmask);
interruptible_sleep_on(&wq->queue);
sigprocmask(SIG_SETMASK, &sigmask, NULL);
} else {
DPRINTK(("autofs_wait: skipped sleeping\n"));
}
status = wq->status;
if ( ! --wq->wait_ctr ) /* Are we the last process to need status? */
kfree(wq);
return status;
}
int autofs_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
{
struct autofs_wait_queue *wq, **wql;
for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) {
if ( wq->wait_queue_token == wait_queue_token )
break;
}
if ( !wq )
return -EINVAL;
*wql = wq->next; /* Unlink from chain */
kfree(wq->name);
wq->name = NULL; /* Do not wait on this queue */
wq->status = status;
if ( ! --wq->wait_ctr ) /* Is anyone still waiting for this guy? */
kfree(wq);
else
wake_up(&wq->queue);
return 0;
}