On 2020/12/9 20:13, Qinglang Miao wrote:
> 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: 8d2451f4994f ("cgroup1: switch to option-by-option parsing")
> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Signed-off-by: Qinglang Miao <miaoqinglang@xxxxxxxxxx>
> ---
> kernel/cgroup/cgroup-v1.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
> index 191c329e4..1fd7d3d18 100644
> --- a/kernel/cgroup/cgroup-v1.c
> +++ b/kernel/cgroup/cgroup-v1.c
> @@ -908,6 +908,9 @@ 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");
"never break user-visible strings such as printk messages because
that breaks the ability to grep for them.", quoted from CodingStyle.
Please fix this and you can add
Reviewed-by: Zefan Li <lizefan@xxxxxxxxxx>
