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fbmem: don't call copy_from/to_user() with mutex held

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Avoid calling copy_from/to_user() with fb_info->lock mutex held in fbmem
ioctl().

fb_mmap() is called under mm->mmap_sem (A) held, that also acquires
fb_info->lock (B); fb_ioctl() takes fb_info->lock (B) and does
copy_from/to_user() that might acquire mm->mmap_sem (A), causing a
deadlock.

NOTE: it doesn't push down the fb_info->lock in each own driver's
fb_ioctl(), so there are still potential deadlocks elsewhere.

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Righi
2009-02-04 15:12:03 -08:00
committed by Linus Torvalds
parent afd8d0f940
commit 1f5e31d7e5
3 changed files with 98 additions and 72 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/video/fbmem.c
+69 -66
View File
@@ -1013,132 +1013,139 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
struct fb_var_screeninfo var;
struct fb_fix_screeninfo fix;
struct fb_con2fbmap con2fb;
struct fb_cmap cmap_from;
struct fb_cmap_user cmap;
struct fb_event event;
void __user *argp = (void __user *)arg;
long ret = 0;
fb = info->fbops;
if (!fb)
return -ENODEV;
switch (cmd) {
case FBIOGET_VSCREENINFO:
ret = copy_to_user(argp, &info->var,
sizeof(var)) ? -EFAULT : 0;
if (!lock_fb_info(info))
return -ENODEV;
var = info->var;
unlock_fb_info(info);
ret = copy_to_user(argp, &var, sizeof(var)) ? -EFAULT : 0;
break;
case FBIOPUT_VSCREENINFO:
if (copy_from_user(&var, argp, sizeof(var))) {
ret = -EFAULT;
break;
}
if (copy_from_user(&var, argp, sizeof(var)))
return -EFAULT;
if (!lock_fb_info(info))
return -ENODEV;
acquire_console_sem();
info->flags |= FBINFO_MISC_USEREVENT;
ret = fb_set_var(info, &var);
info->flags &= ~FBINFO_MISC_USEREVENT;
release_console_sem();
if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
unlock_fb_info(info);
if (!ret && copy_to_user(argp, &var, sizeof(var)))
ret = -EFAULT;
break;
case FBIOGET_FSCREENINFO:
ret = copy_to_user(argp, &info->fix,
sizeof(fix)) ? -EFAULT : 0;
if (!lock_fb_info(info))
return -ENODEV;
fix = info->fix;
unlock_fb_info(info);
ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0;
break;
case FBIOPUTCMAP:
if (copy_from_user(&cmap, argp, sizeof(cmap)))
ret = -EFAULT;
else
ret = fb_set_user_cmap(&cmap, info);
return -EFAULT;
ret = fb_set_user_cmap(&cmap, info);
break;
case FBIOGETCMAP:
if (copy_from_user(&cmap, argp, sizeof(cmap)))
ret = -EFAULT;
else
ret = fb_cmap_to_user(&info->cmap, &cmap);
return -EFAULT;
if (!lock_fb_info(info))
return -ENODEV;
cmap_from = info->cmap;
unlock_fb_info(info);
ret = fb_cmap_to_user(&cmap_from, &cmap);
break;
case FBIOPAN_DISPLAY:
if (copy_from_user(&var, argp, sizeof(var))) {
ret = -EFAULT;
break;
}
if (copy_from_user(&var, argp, sizeof(var)))
return -EFAULT;
if (!lock_fb_info(info))
return -ENODEV;
acquire_console_sem();
ret = fb_pan_display(info, &var);
release_console_sem();
unlock_fb_info(info);
if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
ret = -EFAULT;
return -EFAULT;
break;
case FBIO_CURSOR:
ret = -EINVAL;
break;
case FBIOGET_CON2FBMAP:
if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
ret = -EFAULT;
else if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
ret = -EINVAL;
else {
con2fb.framebuffer = -1;
event.info = info;
event.data = &con2fb;
fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP,
&event);
ret = copy_to_user(argp, &con2fb,
sizeof(con2fb)) ? -EFAULT : 0;
}
return -EFAULT;
if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
return -EINVAL;
con2fb.framebuffer = -1;
event.data = &con2fb;
if (!lock_fb_info(info))
return -ENODEV;
event.info = info;
fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event);
unlock_fb_info(info);
ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0;
break;
case FBIOPUT_CON2FBMAP:
if (copy_from_user(&con2fb, argp, sizeof(con2fb))) {
ret = -EFAULT;
break;
}
if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES) {
ret = -EINVAL;
break;
}
if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX) {
ret = -EINVAL;
break;
}
if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
return -EFAULT;
if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
return -EINVAL;
if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX)
return -EINVAL;
if (!registered_fb[con2fb.framebuffer])
request_module("fb%d", con2fb.framebuffer);
if (!registered_fb[con2fb.framebuffer]) {
ret = -EINVAL;
break;
}
event.info = info;
event.data = &con2fb;
if (!lock_fb_info(info))
return -ENODEV;
event.info = info;
ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP,
&event);
unlock_fb_info(info);
break;
case FBIOBLANK:
if (!lock_fb_info(info))
return -ENODEV;
acquire_console_sem();
info->flags |= FBINFO_MISC_USEREVENT;
ret = fb_blank(info, arg);
info->flags &= ~FBINFO_MISC_USEREVENT;
release_console_sem();
break;;
unlock_fb_info(info);
break;
default:
if (fb->fb_ioctl == NULL)
ret = -ENOTTY;
else
if (!lock_fb_info(info))
return -ENODEV;
fb = info->fbops;
if (fb->fb_ioctl)
ret = fb->fb_ioctl(info, cmd, arg);
else
ret = -ENOTTY;
unlock_fb_info(info);
}
return ret;
}
static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
__acquires(&info->lock)
__releases(&info->lock)
{
struct inode *inode = file->f_path.dentry->d_inode;
int fbidx = iminor(inode);
struct fb_info *info;
long ret;
struct fb_info *info = registered_fb[fbidx];
info = registered_fb[fbidx];
mutex_lock(&info->lock);
ret = do_fb_ioctl(info, cmd, arg);
mutex_unlock(&info->lock);
return ret;
return do_fb_ioctl(info, cmd, arg);
}
#ifdef CONFIG_COMPAT
@@ -1257,8 +1264,6 @@ static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd,
static long fb_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
__acquires(&info->lock)
__releases(&info->lock)
{
struct inode *inode = file->f_path.dentry->d_inode;
int fbidx = iminor(inode);
@@ -1266,7 +1271,6 @@ __releases(&info->lock)
struct fb_ops *fb = info->fbops;
long ret = -ENOIOCTLCMD;
mutex_lock(&info->lock);
switch(cmd) {
case FBIOGET_VSCREENINFO:
case FBIOPUT_VSCREENINFO:
@@ -1292,7 +1296,6 @@ __releases(&info->lock)
ret = fb->fb_compat_ioctl(info, cmd, arg);
break;
}
mutex_unlock(&info->lock);
return ret;
}
#endif