Commit 57ba2c7a authored Dec 10, 2020 by Qinglang Miao Committed by Greg Kroah-Hartman Jan 06, 2021

cgroup: Fix memory leak when parsing multiple source parameters



commit 2d18e54dd8662442ef5898c6bdadeaf90b3cebbc upstream.

A memory leak is found in cgroup1_parse_param() when multiple source
parameters overwrite fc->source in the fs_context struct without free.

unreferenced object 0xffff888100d930e0 (size 16):
  comm "mount", pid 520, jiffies 4303326831 (age 152.783s)
  hex dump (first 16 bytes):
    74 65 73 74 6c 65 61 6b 00 00 00 00 00 00 00 00  testleak........
  backtrace:
    [<000000003e5023ec>] kmemdup_nul+0x2d/0xa0
    [<00000000377dbdaa>] vfs_parse_fs_string+0xc0/0x150
    [<00000000cb2b4882>] generic_parse_monolithic+0x15a/0x1d0
    [<000000000f750198>] path_mount+0xee1/0x1820
    [<0000000004756de2>] do_mount+0xea/0x100
    [<0000000094cafb0a>] __x64_sys_mount+0x14b/0x1f0

Fix this bug by permitting a single source parameter and rejecting with
an error all subsequent ones.

Fixes: 8d2451f4 ("cgroup1: switch to option-by-option parsing")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Reviewed-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 8ddf0285

kernel/cgroup/cgroup-v1.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -914,6 +914,8 @@ int cgroup1_parse_param(struct fs_context fc, struct fs_parameter param)
		opt = fs_parse(fc, &cgroup1_fs_parameters, param, &result);
		if (opt == -ENOPARAM) {
		if (strcmp(param->key, "source") == 0) {
		if (fc->source)
		return invalf(fc, "Multiple sources not supported");
		fc->source = param->string;
		param->string = NULL;
		return 0;