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authorDavid Sterba <dsterba@suse.com>2023-01-24 20:32:10 +0100
committerDavid Sterba <dsterba@suse.com>2023-01-27 14:57:05 +0100
commit33e17b3f5ab74af12aca58c515bc8424ff69a343 (patch)
tree90cbfd5d60eeabb66ea37bbc9ccb10e5eae62846 /fs
parenteadd7deca0ad8a83edb2b894d8326c78e78635d6 (diff)
btrfs: send: limit number of clones and allocated memory size
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/send.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 67f7c698ade3..26dace7b74c6 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -8072,10 +8072,10 @@ 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;
}