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[Linux-fbdev-devel] [PATCH] fbmem: copy_from/to_user() with mutex held (v3) (fwd)
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From: Geert U. <ge...@li...> - 2009-01-22 05:12:50
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Please cc lin...@li...
---------- Forwarded message ----------
Date: Tue, 20 Jan 2009 10:27:56 +0100
From: Andrea Righi <rig...@gm...>
To: Johannes Weiner <ha...@cm...>, Dave Jones <da...@re...>
Cc: Rafael J. Wysocki <rj...@si...>, Johannes Weiner <ha...@sa...>,
Krzysztof Helt <krz...@wp...>,
Harvey Harrison <har...@gm...>,
Stefan Richter <st...@s5...>,
Andrew Morton <ak...@li...>,
LKML <lin...@vg...>, Andrea Righi <rig...@gm...>
Subject: [PATCH] fbmem: copy_from/to_user() with mutex held (v3)
Avoid to call 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're still potential deadlocks somewhere.
ChangeLog (v2 -> v3):
* fix: added a missing unlock_fb_info() in FBIOPUT_VSCREENINFO
(thanks to Krzysztof Helt)
Signed-off-by: Andrea Righi <rig...@gm...>
---
drivers/video/fbcmap.c | 20 +++++--
drivers/video/fbmem.c | 135 ++++++++++++++++++++++++-----------------------
include/linux/fb.h | 15 +++++
3 files changed, 98 insertions(+), 72 deletions(-)
diff --git a/drivers/video/fbcmap.c b/drivers/video/fbcmap.c
index 91b78e6..f53b9f1 100644
--- a/drivers/video/fbcmap.c
+++ b/drivers/video/fbcmap.c
@@ -250,10 +250,6 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
int rc, size = cmap->len * sizeof(u16);
struct fb_cmap umap;
- if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
- !info->fbops->fb_setcmap))
- return -EINVAL;
-
memset(&umap, 0, sizeof(struct fb_cmap));
rc = fb_alloc_cmap(&umap, cmap->len, cmap->transp != NULL);
if (rc)
@@ -262,11 +258,23 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
copy_from_user(umap.green, cmap->green, size) ||
copy_from_user(umap.blue, cmap->blue, size) ||
(cmap->transp && copy_from_user(umap.transp, cmap->transp, size))) {
- fb_dealloc_cmap(&umap);
- return -EFAULT;
+ rc = -EFAULT;
+ goto out;
}
umap.start = cmap->start;
+ if (!lock_fb_info(info)) {
+ rc = -ENODEV;
+ goto out;
+ }
+ if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
+ !info->fbops->fb_setcmap)) {
+ rc = -EINVAL;
+ goto out1;
+ }
rc = fb_set_cmap(&umap, info);
+out1:
+ unlock_fb_info(info);
+out:
fb_dealloc_cmap(&umap);
return rc;
}
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 756efeb..cfd9dce 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -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
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 818fe21..31527e1 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -960,6 +960,21 @@ extern struct fb_info *registered_fb[FB_MAX];
extern int num_registered_fb;
extern struct class *fb_class;
+static inline int lock_fb_info(struct fb_info *info)
+{
+ mutex_lock(&info->lock);
+ if (!info->fbops) {
+ mutex_unlock(&info->lock);
+ return 0;
+ }
+ return 1;
+}
+
+static inline void unlock_fb_info(struct fb_info *info)
+{
+ mutex_unlock(&info->lock);
+}
+
static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch,
u8 *src, u32 s_pitch, u32 height)
{
--
1.5.6.3
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