diff options
Diffstat (limited to '0015-fbdev-fb_pm2fb-Avoid-potential-divide-by-zero-error.patch')
-rw-r--r-- | 0015-fbdev-fb_pm2fb-Avoid-potential-divide-by-zero-error.patch | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/0015-fbdev-fb_pm2fb-Avoid-potential-divide-by-zero-error.patch b/0015-fbdev-fb_pm2fb-Avoid-potential-divide-by-zero-error.patch new file mode 100644 index 000000000000..0b6da2f4f43e --- /dev/null +++ b/0015-fbdev-fb_pm2fb-Avoid-potential-divide-by-zero-error.patch @@ -0,0 +1,50 @@ +From cb4bb011a683532841344ca7f281b5e04389b4f8 Mon Sep 17 00:00:00 2001 +From: Letu Ren <fantasquex@gmail.com> +Date: Thu, 18 Aug 2022 18:44:24 +0800 +Subject: [PATCH 15/73] fbdev: fb_pm2fb: Avoid potential divide by zero error + +commit 19f953e7435644b81332dd632ba1b2d80b1e37af upstream. + +In `do_fb_ioctl()` of fbmem.c, if cmd is FBIOPUT_VSCREENINFO, var will be +copied from user, then go through `fb_set_var()` and +`info->fbops->fb_check_var()` which could may be `pm2fb_check_var()`. +Along the path, `var->pixclock` won't be modified. This function checks +whether reciprocal of `var->pixclock` is too high. If `var->pixclock` is +zero, there will be a divide by zero error. So, it is necessary to check +whether denominator is zero to avoid crash. As this bug is found by +Syzkaller, logs are listed below. + +divide error in pm2fb_check_var +Call Trace: + <TASK> + fb_set_var+0x367/0xeb0 drivers/video/fbdev/core/fbmem.c:1015 + do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110 + fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189 + +Reported-by: Zheyu Ma <zheyuma97@gmail.com> +Signed-off-by: Letu Ren <fantasquex@gmail.com> +Signed-off-by: Helge Deller <deller@gmx.de> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + drivers/video/fbdev/pm2fb.c | 5 +++++ + 1 file changed, 5 insertions(+) + +diff --git a/drivers/video/fbdev/pm2fb.c b/drivers/video/fbdev/pm2fb.c +index d3be2c64f1c0..8fd79deb1e2a 100644 +--- a/drivers/video/fbdev/pm2fb.c ++++ b/drivers/video/fbdev/pm2fb.c +@@ -617,6 +617,11 @@ static int pm2fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) + return -EINVAL; + } + ++ if (!var->pixclock) { ++ DPRINTK("pixclock is zero\n"); ++ return -EINVAL; ++ } ++ + if (PICOS2KHZ(var->pixclock) > PM2_MAX_PIXCLOCK) { + DPRINTK("pixclock too high (%ldKHz)\n", + PICOS2KHZ(var->pixclock)); +-- +2.37.3 + |