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| author | Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2020-07-30 13:47:14 +0300 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-08-04 08:37:23 +0300 |
| commit | d88ca7e1a27eb2df056bbf37ddef62e1c73d37ea (patch) | |
| tree | ab5c93efc1288a746ebeeb3ad98edf1fe022beb3 /drivers/video/fbdev/ps3fb.c | |
| parent | f369bc3f9096f5d355e8b80540bc30ac9a602912 (diff) | |
| download | linux-d88ca7e1a27eb2df056bbf37ddef62e1c73d37ea.tar.xz | |
fbmem: pull fbcon_update_vcs() out of fb_set_var()
syzbot is reporting OOB read bug in vc_do_resize() [1] caused by memcpy()
based on outdated old_{rows,row_size} values, for resize_screen() can
recurse into vc_do_resize() which changes vc->vc_{cols,rows} that outdates
old_{rows,row_size} values which were saved before calling resize_screen().
Daniel Vetter explained that resize_screen() should not recurse into
fbcon_update_vcs() path due to FBINFO_MISC_USEREVENT being still set
when calling resize_screen().
Instead of masking FBINFO_MISC_USEREVENT before calling fbcon_update_vcs(),
we can remove FBINFO_MISC_USEREVENT by calling fbcon_update_vcs() only if
fb_set_var() returned 0. This change assumes that it is harmless to call
fbcon_update_vcs() when fb_set_var() returned 0 without reaching
fb_notifier_call_chain().
[1] https://syzkaller.appspot.com/bug?id=c70c88cfd16dcf6e1d3c7f0ab8648b3144b5b25e
Reported-and-tested-by: syzbot <syzbot+c37a14770d51a085a520@syzkaller.appspotmail.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: kernel test robot <lkp@intel.com> for missing #include
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/075b7e37-3278-cd7d-31ab-c5073cfa8e92@i-love.sakura.ne.jp
Diffstat (limited to 'drivers/video/fbdev/ps3fb.c')
| -rw-r--r-- | drivers/video/fbdev/ps3fb.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/video/fbdev/ps3fb.c b/drivers/video/fbdev/ps3fb.c index 9df78fb77267..203c254f8f6c 100644 --- a/drivers/video/fbdev/ps3fb.c +++ b/drivers/video/fbdev/ps3fb.c @@ -29,6 +29,7 @@ #include <linux/freezer.h> #include <linux/uaccess.h> #include <linux/fb.h> +#include <linux/fbcon.h> #include <linux/init.h> #include <asm/cell-regs.h> @@ -824,12 +825,12 @@ static int ps3fb_ioctl(struct fb_info *info, unsigned int cmd, var = info->var; fb_videomode_to_var(&var, vmode); console_lock(); - info->flags |= FBINFO_MISC_USEREVENT; /* Force, in case only special bits changed */ var.activate |= FB_ACTIVATE_FORCE; par->new_mode_id = val; retval = fb_set_var(info, &var); - info->flags &= ~FBINFO_MISC_USEREVENT; + if (!retval) + fbcon_update_vcs(info, var.activate & FB_ACTIVATE_ALL); console_unlock(); } break; |