@@ -8070,10 +8070,10 @@ long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg)
/*
* Check that we don't overflow at later allocations, we request
* clone_sources_count + 1 items, and compare to unsigned long inside
- * access_ok.
+ * access_ok. Also set an upper limit for allocation size so this can't
+ * easily exhaust memory. Max number of clone sources is about 200K.
*/
- if (arg->clone_sources_count >
- ULONG_MAX / sizeof(struct clone_root) - 1) {
+ if (arg->clone_sources_count > SZ_8M / sizeof(struct clone_root)) {
ret = -EINVAL;
goto out;
}
The arg->clone_sources_count is u64 and can trigger a warning when a huge value is passed from user space and a huge array is allocated. Limit the allocated memory to 8MiB (can be increased if needed), which in turn limits the number of clone sources to 8M / sizeof(struct clone_root) = 8M / 40 = 209715. Real world number of clones is from tens to hundreds, so this is future proof. Reported-by: syzbot+4376a9a073770c173269@syzkaller.appspotmail.com Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/send.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)