4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o <tytso@xxxxxxx> commit bcd8e91f98c156f4b1ebcfacae675f9cfd962441 upstream. A maliciously crafted file system can cause an overflow when the results of a 64-bit calculation is stored into a 32-bit length parameter. https://bugzilla.kernel.org/show_bug.cgi?id=200623 Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Reported-by: Wen Xu <wen.xu@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/ext4.h | 3 +++ fs/ext4/inode.c | 8 ++++++-- 2 files changed, 9 insertions(+), 2 deletions(-) --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -675,6 +675,9 @@ enum { /* Max physical block we can address w/o extents */ #define EXT4_MAX_BLOCK_FILE_PHYS 0xFFFFFFFF +/* Max logical block we can support */ +#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFF + /* * Structure of an inode on the disk */ --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3412,12 +3412,16 @@ static int ext4_iomap_begin(struct inode { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); unsigned int blkbits = inode->i_blkbits; - unsigned long first_block = offset >> blkbits; - unsigned long last_block = (offset + length - 1) >> blkbits; + unsigned long first_block, last_block; struct ext4_map_blocks map; bool delalloc = false; int ret; + if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK) + return -EINVAL; + first_block = offset >> blkbits; + last_block = min_t(loff_t, (offset + length - 1) >> blkbits, + EXT4_MAX_LOGICAL_BLOCK); if (flags & IOMAP_REPORT) { if (ext4_has_inline_data(inode)) {
