Commit 37f32f52 authored by Amir Goldstein's avatar Amir Goldstein
Browse files

ovl: fix memory leak in ovl_parse_param() 



On failure to parse parameters in ovl_parse_param_lowerdir(), it is
necessary to update ctx->nr with the correct nr before using
ovl_reset_lowerdirs() to release l->name.

Reported-and-tested-by: default avatar <syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com>
Fixes: c835110b ("ovl: remove unused code in lowerdir param parsing")
Co-authored-by: default avatarEdward Adam Davis <eadavis@qq.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
parent b28060db

fs/overlayfs/params.c

+5 −6
Original line number Diff line number Diff line
@@ -430,7 +430,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	struct ovl_fs_context *ctx = fc->fs_private;

	struct ovl_fs_context_layer *l;

	char *dup = NULL, *iter;

	ssize_t nr_lower = 0, nr = 0, nr_data = 0;

	ssize_t nr_lower, nr;

	bool data_layer = false;



	/*
@@ -482,6 +482,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
	iter = dup;

	l = ctx->lower;

	for (nr = 0; nr < nr_lower; nr++, l++) {

		ctx->nr++;

		memset(l, 0, sizeof(*l));



		err = ovl_mount_dir(iter, &l->path);
@@ -498,10 +499,10 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
			goto out_put;



		if (data_layer)

			nr_data++;

			ctx->nr_data++;



		/* Calling strchr() again would overrun. */

		if ((nr + 1) == nr_lower)

		if (ctx->nr == nr_lower)

			break;



		err = -EINVAL;
@@ -511,7 +512,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
			 * This is a regular layer so we require that

			 * there are no data layers.

			 */

			if ((ctx->nr_data + nr_data) > 0) {

			if (ctx->nr_data > 0) {

				pr_err("regular lower layers cannot follow data lower layers");

				goto out_put;

			}
@@ -524,8 +525,6 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) 
		data_layer = true;

		iter++;

	}

	ctx->nr = nr_lower;

	ctx->nr_data += nr_data;

	kfree(dup);

	return 0;