Thanks, adding stable.
Saeed
On Oct 22, 2020, at 12:34 AM, Thomas Zimmermann tzimmermann@suse.de wrote:
Hi
On 22.10.20 01:57, saeed.mirzamohammadi@oracle.com wrote:
From: Saeed Mirzamohammadi saeed.mirzamohammadi@oracle.com
This patch fixes the issue due to:
[ 89.572883] divide_error: 0000 [#1] SMP KASAN PTI [ 89.572897] CPU: 3 PID: 16083 Comm: repro Not tainted 5.9.0-rc7.20200930.rc1.allarch-19-g3e32d0d.syzk #5 [ 89.572902] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.5.1 01/01/2011 [ 89.572934] RIP: 0010:cirrusfb_check_var+0x84/0x1260
BTW, if you run qemu with cirrus, there's also a DRM driver named cirrus.ko. Might be a better choice than the old fbdev driver. If you just care about qemu, but not the actual graphics device, take a look at
https://urldefense.com/v3/__https://www.kraxel.org/blog/2014/10/qemu-using-c...
Anyway, thanks for your patch.
Best regards Thomas
The error happens when the pixels value is calculated before performing the sanity checks on bits_per_pixel. A bits_per_pixel set to zero causes divide by zero error.
This patch moves the calculation after the sanity check.
Signed-off-by: Saeed Mirzamohammadi saeed.mirzamohammadi@oracle.com Tested-by: Saeed Mirzamohammadi saeed.mirzamohammadi@oracle.com
drivers/video/fbdev/cirrusfb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/cirrusfb.c b/drivers/video/fbdev/cirrusfb.c index 15a9ee7cd734..a7749101b094 100644 --- a/drivers/video/fbdev/cirrusfb.c +++ b/drivers/video/fbdev/cirrusfb.c @@ -531,7 +531,7 @@ static int cirrusfb_check_var(struct fb_var_screeninfo *var, { int yres; /* memory size in pixels */
- unsigned pixels = info->screen_size * 8 / var->bits_per_pixel;
unsigned int pixels; struct cirrusfb_info *cinfo = info->par;
switch (var->bits_per_pixel) {
@@ -573,6 +573,7 @@ static int cirrusfb_check_var(struct fb_var_screeninfo *var, return -EINVAL; }
- pixels = info->screen_size * 8 / var->bits_per_pixel; if (var->xres_virtual < var->xres) var->xres_virtual = var->xres; /* use highest possible virtual resolution */
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer