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Fri, 13 Jun 2025 22:18:39 -0700 (PDT) From: Alex Guo To: deller@gmx.de Cc: alexguo1023@gmail.com, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH] fbdev: i740: Fix potential divide by zero Date: Sat, 14 Jun 2025 01:18:37 -0400 Message-Id: <20250614051837.3544959-1-alexguo1023@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Variable var->pixclock can be set by user. In case it equals to zero, divide by zero would occur in 4 switch branches in i740fb_decode_var. Similar crashes have happened in other fbdev drivers. We fix this by checking whether 'pixclock' is zero. Similar commit: commit 16844e58704 ("video: fbdev: tridentfb: Error out if 'pixclock' equals zero") Signed-off-by: Alex Guo --- drivers/video/fbdev/i740fb.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c index 9b74dae71472..861e9e397b4e 100644 --- a/drivers/video/fbdev/i740fb.c +++ b/drivers/video/fbdev/i740fb.c @@ -419,6 +419,10 @@ static int i740fb_decode_var(const struct fb_var_screeninfo *var, bpp = var->bits_per_pixel; + if (!var->pixclock){ + dev_err(info->device, "pixclock must not be zero\n"); + return -EINVAL; + } switch (bpp) { case 1 ... 8: bpp = 8;