| Message ID | 20220818181336.3504010-1-syoshida@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | fbcon: Properly revert changes when vc_resize() failed | expand |
Hi Shigeru, On 8/18/22 20:13, Shigeru Yoshida wrote: > fbcon_do_set_font() calls vc_resize() when font size is changed. > However, if if vc_resize() failed, current implementation doesn't > revert changes for font size, and this causes inconsistent state. > > syzbot reported unable to handle page fault due to this issue [1]. > syzbot's repro uses fault injection which cause failure for memory > allocation, so vc_resize() failed. > > This patch fixes this issue by properly revert changes for font > related date when vc_resize() failed. > > Link: https://syzkaller.appspot.com/bug?id=3443d3a1fa6d964dd7310a0cb1696d165a3e07c4 [1] > Reported-by: syzbot+a168dbeaaa7778273c1b@syzkaller.appspotmail.com > Signed-off-by: Shigeru Yoshida <syoshida@redhat.com> applied. Thank you! Helge > --- > drivers/video/fbdev/core/fbcon.c | 27 +++++++++++++++++++++++++-- > 1 file changed, 25 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c > index cf9ac4da0a82..825b012debe7 100644 > --- a/drivers/video/fbdev/core/fbcon.c > +++ b/drivers/video/fbdev/core/fbcon.c > @@ -2401,15 +2401,21 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount, > struct fb_info *info = fbcon_info_from_console(vc->vc_num); > struct fbcon_ops *ops = info->fbcon_par; > struct fbcon_display *p = &fb_display[vc->vc_num]; > - int resize; > + int resize, ret, old_userfont, old_width, old_height, old_charcount; > char *old_data = NULL; > > resize = (w != vc->vc_font.width) || (h != vc->vc_font.height); > if (p->userfont) > old_data = vc->vc_font.data; > vc->vc_font.data = (void *)(p->fontdata = data); > + old_userfont = p->userfont; > if ((p->userfont = userfont)) > REFCOUNT(data)++; > + > + old_width = vc->vc_font.width; > + old_height = vc->vc_font.height; > + old_charcount = vc->vc_font.charcount; > + > vc->vc_font.width = w; > vc->vc_font.height = h; > vc->vc_font.charcount = charcount; > @@ -2425,7 +2431,9 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount, > rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres); > cols /= w; > rows /= h; > - vc_resize(vc, cols, rows); > + ret = vc_resize(vc, cols, rows); > + if (ret) > + goto err_out; > } else if (con_is_visible(vc) > && vc->vc_mode == KD_TEXT) { > fbcon_clear_margins(vc, 0); > @@ -2435,6 +2443,21 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount, > if (old_data && (--REFCOUNT(old_data) == 0)) > kfree(old_data - FONT_EXTRA_WORDS * sizeof(int)); > return 0; > + > +err_out: > + p->fontdata = old_data; > + vc->vc_font.data = (void *)old_data; > + > + if (userfont) { > + p->userfont = old_userfont; > + REFCOUNT(data)--; > + } > + > + vc->vc_font.width = old_width; > + vc->vc_font.height = old_height; > + vc->vc_font.charcount = old_charcount; > + > + return ret; > } > > /*
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index cf9ac4da0a82..825b012debe7 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2401,15 +2401,21 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount, struct fb_info *info = fbcon_info_from_console(vc->vc_num); struct fbcon_ops *ops = info->fbcon_par; struct fbcon_display *p = &fb_display[vc->vc_num]; - int resize; + int resize, ret, old_userfont, old_width, old_height, old_charcount; char *old_data = NULL; resize = (w != vc->vc_font.width) || (h != vc->vc_font.height); if (p->userfont) old_data = vc->vc_font.data; vc->vc_font.data = (void *)(p->fontdata = data); + old_userfont = p->userfont; if ((p->userfont = userfont)) REFCOUNT(data)++; + + old_width = vc->vc_font.width; + old_height = vc->vc_font.height; + old_charcount = vc->vc_font.charcount; + vc->vc_font.width = w; vc->vc_font.height = h; vc->vc_font.charcount = charcount; @@ -2425,7 +2431,9 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount, rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres); cols /= w; rows /= h; - vc_resize(vc, cols, rows); + ret = vc_resize(vc, cols, rows); + if (ret) + goto err_out; } else if (con_is_visible(vc) && vc->vc_mode == KD_TEXT) { fbcon_clear_margins(vc, 0); @@ -2435,6 +2443,21 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount, if (old_data && (--REFCOUNT(old_data) == 0)) kfree(old_data - FONT_EXTRA_WORDS * sizeof(int)); return 0; + +err_out: + p->fontdata = old_data; + vc->vc_font.data = (void *)old_data; + + if (userfont) { + p->userfont = old_userfont; + REFCOUNT(data)--; + } + + vc->vc_font.width = old_width; + vc->vc_font.height = old_height; + vc->vc_font.charcount = old_charcount; + + return ret; } /*
fbcon_do_set_font() calls vc_resize() when font size is changed. However, if if vc_resize() failed, current implementation doesn't revert changes for font size, and this causes inconsistent state. syzbot reported unable to handle page fault due to this issue [1]. syzbot's repro uses fault injection which cause failure for memory allocation, so vc_resize() failed. This patch fixes this issue by properly revert changes for font related date when vc_resize() failed. Link: https://syzkaller.appspot.com/bug?id=3443d3a1fa6d964dd7310a0cb1696d165a3e07c4 [1] Reported-by: syzbot+a168dbeaaa7778273c1b@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida <syoshida@redhat.com> --- drivers/video/fbdev/core/fbcon.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-)