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Fri, 13 Jun 2025 22:29:45 -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: Fix potential divide by zero Date: Sat, 14 Jun 2025 01:29:42 -0400 Message-Id: <20250614052942.3551870-1-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 acornfb_validate_timing. 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/acornfb.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/video/fbdev/acornfb.c b/drivers/video/fbdev/acornfb.c index f0600f6ca254..2dc0e64137e5 100644 --- a/drivers/video/fbdev/acornfb.c +++ b/drivers/video/fbdev/acornfb.c @@ -421,6 +421,8 @@ acornfb_validate_timing(struct fb_var_screeninfo *var, * No need to do long long divisions or anything * like that if you factor it correctly */ + if (!var->pixclock) + return -EINVAL; hs = 1953125000 / var->pixclock; hs = hs * 512 / (var->xres + var->left_margin + var->right_margin + var->hsync_len);