diff options
| author | Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2021-09-08 19:27:49 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-22 11:45:23 +0200 |
| commit | 0a3be6a03a1cea8a02af944087d81b86a32a3941 (patch) | |
| tree | 1b1b102edcff96f2011c0428007709126b1ce4f4 | |
| parent | 3ec364239a7520772b507a09ae48ab96a41ab0eb (diff) | |
fbmem: don't allow too huge resolutions
commit 8c28051cdcbe9dfcec6bd0a4709d67a09df6edae upstream.
syzbot is reporting page fault at vga16fb_fillrect() [1], for
vga16fb_check_var() is failing to detect multiplication overflow.
if (vxres * vyres > maxmem) {
vyres = maxmem / vxres;
if (vyres < yres)
return -ENOMEM;
}
Since no module would accept too huge resolutions where multiplication
overflow happens, let's reject in the common path.
Link: https://syzkaller.appspot.com/bug?extid=04168c8063cfdde1db5e [1]
Reported-by: syzbot <syzbot+04168c8063cfdde1db5e@syzkaller.appspotmail.com>
Debugged-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/185175d6-227a-7b55-433d-b070929b262c@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/video/fbdev/core/fbmem.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 4938ca1f4b63..9087d467cc46 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -34,6 +34,7 @@ #include <linux/fb.h> #include <linux/fbcon.h> #include <linux/mem_encrypt.h> +#include <linux/overflow.h> #include <asm/fb.h> @@ -983,6 +984,7 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) if ((var->activate & FB_ACTIVATE_FORCE) || memcmp(&info->var, var, sizeof(struct fb_var_screeninfo))) { u32 activate = var->activate; + u32 unused; /* When using FOURCC mode, make sure the red, green, blue and * transp fields are set to 0. @@ -1007,6 +1009,11 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) if (var->xres < 8 || var->yres < 8) return -EINVAL; + /* Too huge resolution causes multiplication overflow. */ + if (check_mul_overflow(var->xres, var->yres, &unused) || + check_mul_overflow(var->xres_virtual, var->yres_virtual, &unused)) + return -EINVAL; + ret = info->fbops->fb_check_var(var, info); if (ret) |