scm: lower SCM_MAX_FD

commit bba14de98753cb6599a2dae0e520714b2153522d upstream.

Lower SCM_MAX_FD from 255 to 253 so that allocations for scm_fp_list are
halved. (commit f8d570a4 added two pointers in this structure)

scm_fp_dup() should not copy whole structure (and trigger kmemcheck
warnings), but only the used part. While we are at it, only allocate
needed size.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/include/net/scm.h b/include/net/scm.h
index 8360e47aa7e322336099d09163db1b4254e47016..8b5cccd9eb328134f1dac8c2ec86792b8f56b188 100644 (file)
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -10,11 +10,12 @@
 /* Well, we should have at least one descriptor open
  * to accept passed FDs 8)
  */
-#define SCM_MAX_FD     255
+#define SCM_MAX_FD     253
 
 struct scm_fp_list {
        struct list_head        list;
-       int                     count;
+       short                   count;
+       short                   max;
        struct file             *fp[SCM_MAX_FD];
 };
 

diff --git a/net/core/scm.c b/net/core/scm.c
index b88f6f9d0b97503ddd353e163e73680704cde79a..ddc044816444e75f1301b3ad108ff782c2f1db56 100644 (file)
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -79,10 +79,11 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
                        return -ENOMEM;
                *fplp = fpl;
                fpl->count = 0;
+               fpl->max = SCM_MAX_FD;
        }
        fpp = &fpl->fp[fpl->count];
 
-       if (fpl->count + num > SCM_MAX_FD)
+       if (fpl->count + num > fpl->max)
                return -EINVAL;
 
        /*
@@ -303,11 +304,12 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
        if (!fpl)
                return NULL;
 
-       new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
+       new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
+                         GFP_KERNEL);
        if (new_fpl) {
-               for (i=fpl->count-1; i>=0; i--)
+               for (i = 0; i < fpl->count; i++)
                        get_file(fpl->fp[i]);
-               memcpy(new_fpl, fpl, sizeof(*fpl));
+               new_fpl->max = new_fpl->count;
        }
        return new_fpl;
 }