From: Ritesh Harjani riteshh@linux.ibm.com
commit 175efa81feb8405676e0136d97b10380179c92e0 upstream.
ext4 supports max number of logical blocks in a file to be 0xffffffff. (This is since ext4_extent's ee_block is __le32). This means that EXT4_MAX_LOGICAL_BLOCK should be 0xfffffffe (starting from 0 logical offset). This patch fixes this.
The issue was seen when ext4 moved to iomap_fiemap API and when overlayfs was mounted on top of ext4. Since overlayfs was missing filemap_check_ranges(), so it could pass a arbitrary huge length which lead to overflow of map.m_len logic.
This patch fixes that.
Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework") Reported-by: syzbot+77fa5bdb65cc39711820@syzkaller.appspotmail.com Signed-off-by: Ritesh Harjani riteshh@linux.ibm.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20200505154324.3226743-2-hch@lst.de Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: George Kennedy george.kennedy@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/ext4.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index bf3eaa903033..ae2cb15d9540 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -718,7 +718,7 @@ enum { #define EXT4_MAX_BLOCK_FILE_PHYS 0xFFFFFFFF
/* Max logical block we can support */ -#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFF +#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFE
/* * Structure of an inode on the disk