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fbdev: Fix invalid page access after closing deferred I/O devices 

When a fbdev with deferred I/O is once opened and closed, the dirty
pages still remain queued in the pageref list, and eventually later
those may be processed in the delayed work.  This may lead to a
corruption of pages, hitting an Oops.

This patch makes sure to cancel the delayed work and clean up the
pageref list at closing the device for addressing the bug.  A part of
the cleanup code is factored out as a new helper function that is
called from the common fb_release().

Reviewed-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Miko Larsson <mikoxyzzz@gmail.com>
Fixes: 56c134f7f1 ("fbdev: Track deferred-I/O pages in pageref struct")
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230129082856.22113-1-tiwai@suse.de
This commit is contained in:
Takashi Iwai 2023-01-29 09:28:56 +01:00 committed by Thomas Zimmermann
parent 247a631f9c
commit 3efc61d952
3 changed files with 14 additions and 1 deletions
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10
drivers/video/fbdev/core/fb_defio.c
View File

@ -313,7 +313,7 @@ void fb_deferred_io_open(struct fb_info *info,
}
EXPORT_SYMBOL_GPL(fb_deferred_io_open);
void fb_deferred_io_cleanup(struct fb_info *info)
void fb_deferred_io_release(struct fb_info *info)
{
struct fb_deferred_io *fbdefio = info->fbdefio;
struct page *page;
@ -327,6 +327,14 @@ void fb_deferred_io_cleanup(struct fb_info *info)
page = fb_deferred_io_page(info, i);
page->mapping = NULL;
}
}
EXPORT_SYMBOL_GPL(fb_deferred_io_release);
void fb_deferred_io_cleanup(struct fb_info *info)
{
struct fb_deferred_io *fbdefio = info->fbdefio;
fb_deferred_io_release(info);
kvfree(info->pagerefs);
mutex_destroy(&fbdefio->lock);

4
drivers/video/fbdev/core/fbmem.c
View File

@ -1454,6 +1454,10 @@ __releases(&info->lock)
struct fb_info * const info = file->private_data;
lock_fb_info(info);
#if IS_ENABLED(CONFIG_FB_DEFERRED_IO)
if (info->fbdefio)
fb_deferred_io_release(info);
#endif
if (info->fbops->fb_release)
info->fbops->fb_release(info,1);
module_put(info->fbops->owner);

1
include/linux/fb.h
View File

@ -662,6 +662,7 @@ extern int fb_deferred_io_init(struct fb_info *info);
extern void fb_deferred_io_open(struct fb_info *info,
struct inode *inode,
struct file *file);
extern void fb_deferred_io_release(struct fb_info *info);
extern void fb_deferred_io_cleanup(struct fb_info *info);
extern int fb_deferred_io_fsync(struct file *file, loff_t start,
loff_t end, int datasync);