This is a note to let you know that I've just added the patch titled
btrfs: send: limit number of clones and allocated memory size
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-send-limit-number-of-clones-and-allocated-memo.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c853ef438e2e2941bb50c9affc3614a2c18817a1
Author: David Sterba <dsterba@xxxxxxxx>
Date: Tue Jan 24 20:32:10 2023 +0100
btrfs: send: limit number of clones and allocated memory size
[ 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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 1c4b693ee4a3a..937b60ae576e0 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -7839,10 +7839,10 @@ 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;
}
