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([115.25.44.221]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-345b053038fsm623686a91.14.2025.11.17.23.33.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Nov 2025 23:33:46 -0800 (PST) From: Jiaming Zhang To: linkinjeon@kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, r772577952@gmail.com, sj1557.seo@samsung.com, syzkaller@googlegroups.com, yuezhang.mo@sony.com Subject: [PATCH 1/1] exfat: fix divide error in exfat_allocate_bitmap() Date: Tue, 18 Nov 2025 15:33:38 +0800 Message-Id: <20251118073338.576334-2-r772577952@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251118073338.576334-1-r772577952@gmail.com> References: <20251118073338.576334-1-r772577952@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The variable max_ra_count in exfat_allocate_bitmap() can be 0, leading to a divide-by-zero error in the modulo operation (i % max_ra_count) inside the loop. Avoid this by adding a check for max_ra_count before performing the modulo operation. Fixes: 9fd688678dd8 Closes: https://lore.kernel.org/lkml/CANypQFb0NeToJrTY5PQi57K_440xQJ1uUS2pM= OKqLsqTdEGbRw@mail.gmail.com/ Suggested-by: Namjae Jeon Signed-off-by: Jiaming Zhang --- 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 2d2d510f2372..0b6466b3490a 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 =3D 0; i < sbi->map_sectors; i++) { /* Trigger the next readahead in advance. */ - if (0 =3D=3D (i % max_ra_count)) { + if (max_ra_count && 0 =3D=3D (i % max_ra_count)) { blk_start_plug(&plug); for (j =3D i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++) sb_breadahead(sb, sector + j); --=20 2.34.1