From: Zheyu Ma zheyuma97@gmail.com
[ Upstream commit 6ba592fa014f21f35a8ee8da4ca7b95a018f13e8 ]
In the function s3fb_set_par(), the value of 'screen_size' is calculated by the user input. If the user provides the improper value, the value of 'screen_size' may larger than 'info->screen_size', which may cause the following bug:
[ 54.083733] BUG: unable to handle page fault for address: ffffc90003000000 [ 54.083742] #PF: supervisor write access in kernel mode [ 54.083744] #PF: error_code(0x0002) - not-present page [ 54.083760] RIP: 0010:memset_orig+0x33/0xb0 [ 54.083782] Call Trace: [ 54.083788] s3fb_set_par+0x1ec6/0x4040 [ 54.083806] fb_set_var+0x604/0xeb0 [ 54.083836] do_fb_ioctl+0x234/0x670
Fix the this by checking the value of 'screen_size' before memset_io().
Fixes: a268422de8bf ("fbdev driver for S3 Trio/Virge") Signed-off-by: Zheyu Ma zheyuma97@gmail.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/s3fb.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/video/fbdev/s3fb.c b/drivers/video/fbdev/s3fb.c index 5c74253e7b2c..a936455a3df2 100644 --- a/drivers/video/fbdev/s3fb.c +++ b/drivers/video/fbdev/s3fb.c @@ -902,6 +902,8 @@ static int s3fb_set_par(struct fb_info *info) value = clamp((htotal + hsstart + 1) / 2 + 2, hsstart + 4, htotal + 1); svga_wcrt_multi(par->state.vgabase, s3_dtpc_regs, value);
+ if (screen_size > info->screen_size) + screen_size = info->screen_size; memset_io(info->screen_base, 0x00, screen_size); /* Device and screen back on */ svga_wcrt_mask(par->state.vgabase, 0x17, 0x80, 0x80);