On Sun 12-04-20 14:54:35, Ritesh Harjani wrote: > EXT4_MAX_LOGICAL_BLOCK - map.m_lblk + 1 in case when > map.m_lblk (offset) is 0 could overflow an unsigned int > and become 0. > > Fix this. > > Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> > Reported-by: syzbot+77fa5bdb65cc39711820@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework") The patch looks good to me. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > fs/ext4/inode.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index e416096fc081..d630ec7a9c8e 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3424,6 +3424,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, > int ret; > struct ext4_map_blocks map; > u8 blkbits = inode->i_blkbits; > + loff_t len; > > if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK) > return -EINVAL; > @@ -3435,8 +3436,11 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, > * Calculate the first and last logical blocks respectively. > */ > map.m_lblk = offset >> blkbits; > - map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits, > + len = min_t(loff_t, (offset + length - 1) >> blkbits, > EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1; > + if (len > EXT4_MAX_LOGICAL_BLOCK) > + len = EXT4_MAX_LOGICAL_BLOCK; > + map.m_len = len; > > if (flags & IOMAP_WRITE) > ret = ext4_iomap_alloc(inode, &map, flags); > @@ -3524,6 +3528,7 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset, > bool delalloc = false; > struct ext4_map_blocks map; > u8 blkbits = inode->i_blkbits; > + loff_t len > > if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK) > return -EINVAL; > @@ -3541,8 +3546,11 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset, > * Calculate the first and last logical block respectively. > */ > map.m_lblk = offset >> blkbits; > - map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits, > + len = min_t(loff_t, (offset + length - 1) >> blkbits, > EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1; > + if (len > EXT4_MAX_LOGICAL_BLOCK) > + len = EXT4_MAX_LOGICAL_BLOCK; > + map.m_len = len; > > /* > * Fiemap callers may call for offset beyond s_bitmap_maxbytes. > -- > 2.21.0 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR