On Fri, Sep 20, 2024 at 08:28:51PM +0800, Julian Sun wrote: > The overflow check in generic_copy_file_checks() and generic_remap_checks() > is now broken because the result of the addition is implicitly converted to > an unsigned type, which disrupts the comparison with signed numbers. > This caused the kernel to not return EOVERFLOW in copy_file_range() > call with len is set to 0xffffffffa003e45bul. > > Use the check_add_overflow() macro to fix this issue. > > Reported-and-tested-by: syzbot+296b1c84b9cbf306e5a0@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=296b1c84b9cbf306e5a0 > Fixes: 1383a7ed6749 ("vfs: check file ranges before cloning files") > Fixes: 96e6e8f4a68d ("vfs: add missing checks to copy_file_range") > Inspired-by: Dave Chinner <david@xxxxxxxxxxxxx> > Reviewed-by: Jan Kara <jack@xxxxxxx> > Signed-off-by: Julian Sun <sunjunchao2870@xxxxxxxxx> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> --D > --- > fs/read_write.c | 5 +++-- > fs/remap_range.c | 5 +++-- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/read_write.c b/fs/read_write.c > index 070a7c33b9dd..5211246edc2e 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -1509,7 +1509,7 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, > struct inode *inode_in = file_inode(file_in); > struct inode *inode_out = file_inode(file_out); > uint64_t count = *req_count; > - loff_t size_in; > + loff_t size_in, tmp; > int ret; > > ret = generic_file_rw_checks(file_in, file_out); > @@ -1544,7 +1544,8 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, > return -ETXTBSY; > > /* Ensure offsets don't wrap. */ > - if (pos_in + count < pos_in || pos_out + count < pos_out) > + if (check_add_overflow(pos_in, count, &tmp) || > + check_add_overflow(pos_out, count, &tmp)) > return -EOVERFLOW; > > /* Shorten the copy to EOF */ > diff --git a/fs/remap_range.c b/fs/remap_range.c > index 28246dfc8485..6fdeb3c8cb70 100644 > --- a/fs/remap_range.c > +++ b/fs/remap_range.c > @@ -36,7 +36,7 @@ static int generic_remap_checks(struct file *file_in, loff_t pos_in, > struct inode *inode_out = file_out->f_mapping->host; > uint64_t count = *req_count; > uint64_t bcount; > - loff_t size_in, size_out; > + loff_t size_in, size_out, tmp; > loff_t bs = inode_out->i_sb->s_blocksize; > int ret; > > @@ -45,7 +45,8 @@ static int generic_remap_checks(struct file *file_in, loff_t pos_in, > return -EINVAL; > > /* Ensure offsets don't wrap. */ > - if (pos_in + count < pos_in || pos_out + count < pos_out) > + if (check_add_overflow(pos_in, count, &tmp) || > + check_add_overflow(pos_out, count, &tmp)) > return -EINVAL; > > size_in = i_size_read(inode_in); > -- > 2.39.2 > >
