From 1f5e31d7e55ac7fbd4ec5e5b20c8868b0e4564c9 Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Wed, 4 Feb 2009 15:12:03 -0800 Subject: [PATCH] fbmem: don't call copy_from/to_user() with mutex held 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 Cc: Dave Jones Cc: "Rafael J. Wysocki" Cc: Johannes Weiner Cc: Krzysztof Helt Cc: Harvey Harrison Cc: Stefan Richter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 91b78e691505..f53b9f1d6aba 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 756efeb91abc..cfd9dce1ce0b 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 818fe21257e8..31527e17076b 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) { -- 2.30.2