From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5B9E41E0DD9 for ; Tue, 18 Nov 2025 02:48:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763434105; cv=none; b=JiXS+iM3OphcrHWCAFOIkiLU1ziTWXvHF8qqtMNfHxyd/Jw4WEMLiE0+dNATk7gLg1k1JtaGlzmJKjFvGMwWJ9oJaN6R1RkG0rqQAapSF+snH+a+lsppAKfIZWupXF7VdwrUDSDBe+2o/5khKynkh6VrRArAK8QU+AiqzTi91jg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763434105; c=relaxed/simple; bh=RNzuOfhnaaoIPT/hhpurTDMUrMFWpoGZ1URc7azveIY=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=hw6tXD1SKYnii1reTqcnCk2w2TrBEuZYr7Em2mma+hhPlWDc9gr24i083RiBYAiNLmYPgWHsx0sbGll6oyL13uo/Pbiw4ntLz1caUKy6HzCbh7QQlC1bV+FKXZKg7sg5mbOAkGnq6fHuTKVOkOeNW4lfyZD9N5ThUE07gtA8oQA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=kernel.org; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.210.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pf1-f170.google.com with SMTP id d2e1a72fcca58-7aab061e7cbso5621663b3a.1 for ; Mon, 17 Nov 2025 18:48:24 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763434103; x=1764038903; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=RFRzafrM6Eva6+M5WExAq5JV9s+bKfFRLI1WdLs+7Kg=; b=t9c/1PnW8bzXq0d96lB3tMKbxsg+iHCRlTrjYyj6HUoFUbDUq/M17RRlyzMnOzR0a6 jpiuS25BLMqGlHa4NB2P8P/vuVGW1EIDwOmNJQOsfEOzuW/duoaPvLZ/G8EGkm61hjm8 0rUjB8xumlEJ9d0pL6oEfaIv9x0POE+8ykjjfHrl1cQEjPyeD5UH5CM5wBnwwvVG97qW iTXdpGYxZCPt2qdh5kash/iKNCCS1QtTrWft+2KQdeskC3CKE8xe4vzI4xZEDZ4kvFJs gumk2oBxRmd61SDG60ZA44CAe+4GnGJKDBtcX98fucxiBCoAJXucE+TSUZJTdmi61AnE x1Gg== X-Gm-Message-State: AOJu0YxLdA1MkZ3MwJLV1A1q7rw/sGPmwBv/MBo1+JRZXh/NFn/0z9Nq U2N/l9SHFnCFiTvanV5EDUWfSfp1pIEP5UHFKrTMy0a8Uo1SpEEiScdz X-Gm-Gg: ASbGncv5Hx+m/eWq4X8Gu39mDT8bwgMIbUE9KVYVTpJm6Y3ynZeYuvwUBgdzXpEujk8 tjW69EqsP7hR+4lVYfT4RRiRekpF9JUSCFK9kJ/d5p3z2icKlJE5MYovkC5l9rFQMSOygapfB+5 xTGPTRKOCbsYOftsIrf/Zmh/weK348/qdR+zmL5CQOxY4g5wsmiPaYMu+oKw3xdbLikwpngEXnS Pv/bRCAHRKbDfVbqeVLwmcMn5kD8/M9n+VshT3OI/RMOX3K1QqjWHo+mWVxZQFIEVL8BAQ8l2YJ x5FudwoKZd2qpsuB1Zeq/XZWSSbSKODc0DT+kmeBC00OWu1OofBwRouVZVcguqxDfj/fq9XtiHr BRfgyU9VNZKWwXoopgDYAORYK1pbq/JSbQoJXl6Wm9Zkuzi3nPEtE/Wu8kc9LaXEjN3J0/fyZBS y7XsWfIHt7/JTD5SbcbXyv9OvQAQ== X-Google-Smtp-Source: AGHT+IGlJv7sR+AI1gk41lPOdUK0NOGCgkmiOfUU6drXPL+od9OGfeLZVrAtIy2n17APvDcanj6FAA== X-Received: by 2002:a05:6a20:6a21:b0:342:a261:e2bc with SMTP id adf61e73a8af0-35b9f7802fdmr19744524637.10.1763434103453; Mon, 17 Nov 2025 18:48:23 -0800 (PST) Received: from localhost.localdomain ([1.227.206.162]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-bc36e8a58cfsm13485846a12.10.2025.11.17.18.48.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Nov 2025 18:48:22 -0800 (PST) From: Namjae Jeon To: sj1557.seo@samsung.com, yuezhang.mo@sony.com Cc: linux-fsdevel@vger.kernel.org, Namjae Jeon , Jiaming Zhang Subject: [PATCH] exfat: fix divide-by-zero in exfat_allocate_bitmap Date: Tue, 18 Nov 2025 11:48:04 +0900 Message-Id: <20251118024804.7143-1-linkinjeon@kernel.org> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The variable max_ra_count can be 0 in exfat_allocate_bitmap(), which causes a divide-by-zero error in the subsequent modulo operation (i % max_ra_count), leading to a system crash. When max_ra_count is 0, it means that readahead is not used. This patch load the bitmap without readahead. Reported-by: Jiaming Zhang Signed-off-by: Namjae Jeon --- fs/exfat/balloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index b387bf7df65e..5429041c7eaf 100644 --- a/fs/exfat/balloc.c +++ b/fs/exfat/balloc.c @@ -106,7 +106,7 @@ static int exfat_allocate_bitmap(struct super_block *sb, (PAGE_SHIFT - sb->s_blocksize_bits); for (i = 0; i < sbi->map_sectors; i++) { /* Trigger the next readahead in advance. */ - if (0 == (i % max_ra_count)) { + if (max_ra_count && 0 == (i % max_ra_count)) { blk_start_plug(&plug); for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++) sb_breadahead(sb, sector + j); -- 2.25.1