diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-05-08 20:11:50 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-05-11 04:52:45 +0300 |
| commit | 7172dc93d621d5dc302d007e95ddd1311ec64283 (patch) | |
| tree | 9dcbc685a20185bd292a3e7042c42da430bf310f /net | |
| parent | 84c8b7ad5e748c0b93415b060c7071f8c524f4f5 (diff) | |
| download | linux-7172dc93d621d5dc302d007e95ddd1311ec64283.tar.xz | |
af_unix: Add dead flag to struct scm_fp_list.
Commit 1af2dface5d2 ("af_unix: Don't access successor in unix_del_edges()
during GC.") fixed use-after-free by avoid accessing edge->successor while
GC is in progress.
However, there could be a small race window where another process could
call unix_del_edges() while gc_in_progress is true and __skb_queue_purge()
is on the way.
So, we need another marker for struct scm_fp_list which indicates if the
skb is garbage-collected.
This patch adds dead flag in struct scm_fp_list and set it true before
calling __skb_queue_purge().
Fixes: 1af2dface5d2 ("af_unix: Don't access successor in unix_del_edges() during GC.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240508171150.50601-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/scm.c | 1 | ||||
| -rw-r--r-- | net/unix/garbage.c | 14 |
2 files changed, 11 insertions, 4 deletions
diff --git a/net/core/scm.c b/net/core/scm.c index 5763f3320358..4f6a14babe5a 100644 --- a/net/core/scm.c +++ b/net/core/scm.c @@ -91,6 +91,7 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp) fpl->user = NULL; #if IS_ENABLED(CONFIG_UNIX) fpl->inflight = false; + fpl->dead = false; fpl->edges = NULL; INIT_LIST_HEAD(&fpl->vertices); #endif diff --git a/net/unix/garbage.c b/net/unix/garbage.c index d76450133e4f..1f8b8cdfcdc8 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -158,13 +158,11 @@ static void unix_add_edge(struct scm_fp_list *fpl, struct unix_edge *edge) unix_update_graph(unix_edge_successor(edge)); } -static bool gc_in_progress; - static void unix_del_edge(struct scm_fp_list *fpl, struct unix_edge *edge) { struct unix_vertex *vertex = edge->predecessor->vertex; - if (!gc_in_progress) + if (!fpl->dead) unix_update_graph(unix_edge_successor(edge)); list_del(&edge->vertex_entry); @@ -240,7 +238,7 @@ void unix_del_edges(struct scm_fp_list *fpl) unix_del_edge(fpl, edge); } while (i < fpl->count_unix); - if (!gc_in_progress) { + if (!fpl->dead) { receiver = fpl->edges[0].successor; receiver->scm_stat.nr_unix_fds -= fpl->count_unix; } @@ -559,9 +557,12 @@ static void unix_walk_scc_fast(struct sk_buff_head *hitlist) list_replace_init(&unix_visited_vertices, &unix_unvisited_vertices); } +static bool gc_in_progress; + static void __unix_gc(struct work_struct *work) { struct sk_buff_head hitlist; + struct sk_buff *skb; spin_lock(&unix_gc_lock); @@ -579,6 +580,11 @@ static void __unix_gc(struct work_struct *work) spin_unlock(&unix_gc_lock); + skb_queue_walk(&hitlist, skb) { + if (UNIXCB(skb).fp) + UNIXCB(skb).fp->dead = true; + } + __skb_queue_purge(&hitlist); skip_gc: WRITE_ONCE(gc_in_progress, false); |