From fe23cb65c2c394ea306f3714a17d46ab2e6a0af1 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 22 Mar 2018 11:50:26 -0400 Subject: ext4: fix offset overflow on 32-bit archs in ext4_iomap_begin() 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 --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 9acac476c15c..d8a692f04156 100644 --- 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) { -- cgit v1.2.3-55-g7522