On Mon, Apr 14, 2014 at 9:02 AM, Masami Ichikawa <masami...@gmail.com> wrote:
> kmemleak reported some memory leak as below.
grrr. yes. sorry.
> unreferenced object 0xffff8800d6ea4000 (size 512):
> comm "sshd", pid 278, jiffies 4294898315 (age 46.653s)
> hex dump (first 32 bytes):
> 21 00 00 00 04 00 00 00 15 00 01 00 3e 00 00 c0 !...........>...
> 06 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00 ........!.......
> backtrace:
> [<ffffffff8151414e>] kmemleak_alloc+0x4e/0xb0
> [<ffffffff811a3a40>] __kmalloc+0x280/0x320
> [<ffffffff8110842e>] prctl_set_seccomp+0x11e/0x3b0
> [<ffffffff8107bb6b>] SyS_prctl+0x3bb/0x4a0
> [<ffffffff8152ef2d>] system_call_fastpath+0x1a/0x1f
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> This memory leak happend in seccomp_attach_filter().
> The fp pointer was allocated via kzalloc so that it needs to realase memory
> when leaving from function.
>
> This patch changed two things.
> One is set -ENOMEM to ret, if fp is unable to get memory.
> The other is removes "return 0" statement, and frees fp pointer before
> leaving.
>
> Signed-off-by: Masami Ichikawa <masami...@gmail.com>
> ---
> kernel/seccomp.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index d8d046c..a9ce7a9 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -259,8 +259,10 @@ static long seccomp_attach_filter(struct sock_fprog
> *fprog)
> filter = kzalloc(sizeof(struct seccomp_filter) +
> sizeof(struct sock_filter_int) * new_len,
> GFP_KERNEL|__GFP_NOWARN);
> - if (!filter)
> + if (!filter) {
> + ret = -ENOMEM;
> goto free_prog;
> + }
agree. that's a good addition.
> ret = sk_convert_filter(fp, fprog->len, filter->insnsi, &new_len);
> if (ret)
> @@ -275,10 +277,10 @@ static long seccomp_attach_filter(struct sock_fprog
> *fprog)
> */
> filter->prev = current->seccomp.filter;
> current->seccomp.filter = filter;
> - return 0;
I think mixing error and ok return paths is ugly.
Can you add kfree(fp) here instead of removing return 0?
Thanks!
> free_filter:
> - kfree(filter);
> + if (ret)
> + kfree(filter);
> free_prog:
> kfree(fp);
> return ret;
> --
> 1.9.1
>
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