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FAILED: patch "[PATCH] btrfs: validate qgroup inherit for SNAP_CREATE_V2 ioctl" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Mar 7, 2021

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The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5011c5a663b9c6d6aff3d394f11049b371199627 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <[email protected]>
Date: Wed, 17 Feb 2021 09:04:34 +0300
Subject: [PATCH] btrfs: validate qgroup inherit for SNAP_CREATE_V2 ioctl

The problem is we're copying "inherit" from user space but we don't necessarily know that we're copying enough data for a 64 byte struct. Then the next problem is that 'inherit' has a variable size array at the end, and we have to verify that array is the size we expected.

Fixes 6f72c7e20dba ("Btrfs: add qgroup inheritance")
CC [email protected] # 4.4+
Signed-off-by Dan Carpenter <[email protected]>
Reviewed-by David Sterba <[email protected]>
Signed-off-by David Sterba <[email protected]>
fs/btrfs/ioctl.c +18 -1
index a8c60d46d19c..1b837c08ca90 100644
@@ -1935,7 +1935,10 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
 	if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
 		readonly = true;
 	if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
-		if (vol_args->size > PAGE_SIZE) {
+		u64 nums;
+
+		if (vol_args->size < sizeof(*inherit) ||
+		    vol_args->size > PAGE_SIZE) {
 			ret = -EINVAL;
 			goto free_args;
 		}

@@ -1944,6 +1947,20 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
 			ret = PTR_ERR(inherit);
 			goto free_args;
 		}
+
+		if (inherit->num_qgroups > PAGE_SIZE ||
+		    inherit->num_ref_copies > PAGE_SIZE ||
+		    inherit->num_excl_copies > PAGE_SIZE) {
+			ret = -EINVAL;
+			goto free_inherit;
+		}
+
+		nums = inherit->num_qgroups + 2 * inherit->num_ref_copies +
+		       2 * inherit->num_excl_copies;
+		if (vol_args->size != struct_size(inherit, qgroups, nums)) {
+			ret = -EINVAL;
+			goto free_inherit;
+		}
 	}
 
 	ret = __btrfs_ioctl_snap_create(file, vol_args->name, vol_args->fd,