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authorDavid S. Miller <davem@davemloft.net>2008-11-07 02:45:32 +0300
committerDavid S. Miller <davem@davemloft.net>2008-11-07 02:45:32 +0300
commit3b53fbf4314594fa04544b02b2fc6e607912da18 (patch)
treeaf88f6c7ecbdf06719c92cc8891f75f497b70555 /net
parent518a09ef11f8454f4676125d47c3e775b300c6a5 (diff)
downloadlinux-3b53fbf4314594fa04544b02b2fc6e607912da18.tar.xz
net: Fix recursive descent in __scm_destroy().
__scm_destroy() walks the list of file descriptors in the scm_fp_list pointed to by the scm_cookie argument. Those, in turn, can close sockets and invoke __scm_destroy() again. There is nothing which limits how deeply this can occur. The idea for how to fix this is from Linus. Basically, we do all of the fput()s at the top level by collecting all of the scm_fp_list objects hit by an fput(). Inside of the initial __scm_destroy() we keep running the list until it is empty. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/scm.c24
1 files changed, 21 insertions, 3 deletions
diff --git a/net/core/scm.c b/net/core/scm.c
index 10f5c65f6a47..ab242cc1acca 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -75,6 +75,7 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
if (!fpl)
return -ENOMEM;
*fplp = fpl;
+ INIT_LIST_HEAD(&fpl->list);
fpl->count = 0;
}
fpp = &fpl->fp[fpl->count];
@@ -106,9 +107,25 @@ void __scm_destroy(struct scm_cookie *scm)
if (fpl) {
scm->fp = NULL;
- for (i=fpl->count-1; i>=0; i--)
- fput(fpl->fp[i]);
- kfree(fpl);
+ if (current->scm_work_list) {
+ list_add_tail(&fpl->list, current->scm_work_list);
+ } else {
+ LIST_HEAD(work_list);
+
+ current->scm_work_list = &work_list;
+
+ list_add(&fpl->list, &work_list);
+ while (!list_empty(&work_list)) {
+ fpl = list_first_entry(&work_list, struct scm_fp_list, list);
+
+ list_del(&fpl->list);
+ for (i=fpl->count-1; i>=0; i--)
+ fput(fpl->fp[i]);
+ kfree(fpl);
+ }
+
+ current->scm_work_list = NULL;
+ }
}
}
@@ -284,6 +301,7 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
if (new_fpl) {
+ INIT_LIST_HEAD(&new_fpl->list);
for (i=fpl->count-1; i>=0; i--)
get_file(fpl->fp[i]);
memcpy(new_fpl, fpl, sizeof(*fpl));