From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiri Slaby , Jan Kara , Theodore Tso Subject: [PATCH 4.16 090/196] ext4: fix offset overflow on 32-bit archs in ext4_iomap_begin() Date: Sun, 22 Apr 2018 15:51:50 +0200 Message-Id: <20180422135108.945904552@linuxfoundation.org> In-Reply-To: <20180422135104.278511750@linuxfoundation.org> References: <20180422135104.278511750@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiri Slaby commit fe23cb65c2c394ea306f3714a17d46ab2e6a0af1 upstream. ext4_iomap_begin() has a bug where offset returned in the iomap structure will be truncated to unsigned long size. On 64-bit architectures this is fine but on 32-bit architectures obviously not. Not many places actually use the offset stored in the iomap structure but one of visible failures is in SEEK_HOLE / SEEK_DATA implementation. If we create a file like: dd if=/dev/urandom of=file bs=1k seek=8m count=1 then lseek64("file", 0x100000000ULL, SEEK_DATA) wrongly returns 0x100000000 on unfixed kernel while it should return 0x200000000. Avoid the overflow by proper type cast. Fixes: 545052e9e35a ("ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA") Signed-off-by: Jiri Slaby Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org # v4.15 Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3524,7 +3524,7 @@ retry: iomap->flags |= IOMAP_F_DIRTY; iomap->bdev = inode->i_sb->s_bdev; iomap->dax_dev = sbi->s_daxdev; - iomap->offset = first_block << blkbits; + iomap->offset = (u64)first_block << blkbits; iomap->length = (u64)map.m_len << blkbits; if (ret == 0) {