seccomp: fix memory leak on filter attach
authorKees Cook <keescook@chromium.org>
Wed, 16 Apr 2014 17:54:34 +0000 (10:54 -0700)
committerDavid S. Miller <davem@davemloft.net>
Wed, 16 Apr 2014 19:25:53 +0000 (15:25 -0400)
This sets the correct error code when final filter memory is unavailable,
and frees the raw filter no matter what.

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

Reported-by: Masami Ichikawa <masami256@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Masami Ichikawa <masami256@gmail.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
kernel/seccomp.c

index 590c37925084d08e046e6f51de58a4845b7d5f72..b35c21503a36d6e63160f7f46a2eb7bf59d371ce 100644 (file)
@@ -255,6 +255,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
                goto free_prog;
 
        /* Allocate a new seccomp_filter */
+       ret = -ENOMEM;
        filter = kzalloc(sizeof(struct seccomp_filter) +
                         sizeof(struct sock_filter_int) * new_len,
                         GFP_KERNEL|__GFP_NOWARN);
@@ -264,6 +265,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
        ret = sk_convert_filter(fp, fprog->len, filter->insnsi, &new_len);
        if (ret)
                goto free_filter;
+       kfree(fp);
 
        atomic_set(&filter->usage, 1);
        filter->len = new_len;