From: David Sterba dsterba@suse.com
[ Upstream commit 33e17b3f5ab74af12aca58c515bc8424ff69a343 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/send.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index efab9446eac87..b08e7fcd8c34d 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6646,10 +6646,10 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *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; }