lkml.org 
[lkml]   [2018]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCHv2 net 3/3] sctp: fa_resize sctp stream instead of redo fa_alloc
Date
Now when doing 4-shakehand or adding new streams, sctp has to allocate
new memory for asoc->stream and copy the old stream's information from
the old asoc->stream to the new one. It also cause the stream pointers
to change, by which a panic was even caused due to stream->out_curr's
change.

To fix this, flex_array_resize() is used in sctp_stream_alloc_out/in()
when asoc->stream has been allocated. Besides, with this asoc->stream
will only be allocated once, and grow or shrink dynamically later.

Note that flex_array_prealloc() is needed before growing as fa_alloc
does, while flex_array_clear() and flex_array_shrink() are called to
free the unused memory before shrinking.

Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations")
Reported-by: Ying Xu <yinxu@redhat.com>
Reported-by: syzbot+e33a3a138267ca119c7d@syzkaller.appspotmail.com
Suggested-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
---
net/sctp/stream.c | 87 +++++++++++++++++++++++++------------------------------
1 file changed, 40 insertions(+), 47 deletions(-)

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index 3892e76..aff30b2 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -37,6 +37,17 @@
#include <net/sctp/sm.h>
#include <net/sctp/stream_sched.h>

+static void fa_zero(struct flex_array *fa, size_t index, size_t count)
+{
+ void *elem;
+
+ while (count--) {
+ elem = flex_array_get(fa, index);
+ memset(elem, 0, fa->element_size);
+ index++;
+ }
+}
+
static struct flex_array *fa_alloc(size_t elem_size, size_t elem_count,
gfp_t gfp)
{
@@ -48,8 +59,9 @@ static struct flex_array *fa_alloc(size_t elem_size, size_t elem_count,
err = flex_array_prealloc(result, 0, elem_count, gfp);
if (err) {
flex_array_free(result);
- result = NULL;
+ return NULL;
}
+ fa_zero(result, 0, elem_count);
}

return result;
@@ -61,27 +73,28 @@ static void fa_free(struct flex_array *fa)
flex_array_free(fa);
}

-static void fa_copy(struct flex_array *fa, struct flex_array *from,
- size_t index, size_t count)
+static int fa_resize(struct flex_array *fa, size_t count, gfp_t gfp)
{
- void *elem;
+ int nr = fa->total_nr_elements, n;

- while (count--) {
- elem = flex_array_get(from, index);
- flex_array_put(fa, index, elem, 0);
- index++;
+ if (count > nr) {
+ if (flex_array_resize(fa, count, gfp))
+ return -ENOMEM;
+ if (flex_array_prealloc(fa, nr, count - nr, gfp))
+ return -ENOMEM;
+ fa_zero(fa, nr, count - nr);
+
+ return 0;
}
-}

-static void fa_zero(struct flex_array *fa, size_t index, size_t count)
-{
- void *elem;
+ /* Shrink the unused memory,
+ * FLEX_ARRAY_FREE check is safe for sctp stream.
+ */
+ for (n = count; n < nr; n++)
+ flex_array_clear(fa, n);
+ flex_array_shrink(fa);

- while (count--) {
- elem = flex_array_get(fa, index);
- memset(elem, 0, fa->element_size);
- index++;
- }
+ return flex_array_resize(fa, count, gfp);
}

/* Migrates chunks from stream queues to new stream queues if needed,
@@ -138,47 +151,27 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream,
static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
gfp_t gfp)
{
- struct flex_array *out;
- size_t elem_size = sizeof(struct sctp_stream_out);
-
- out = fa_alloc(elem_size, outcnt, gfp);
- if (!out)
- return -ENOMEM;
+ if (!stream->out) {
+ stream->out = fa_alloc(sizeof(struct sctp_stream_out),
+ outcnt, gfp);

- if (stream->out) {
- fa_copy(out, stream->out, 0, min(outcnt, stream->outcnt));
- fa_free(stream->out);
+ return stream->out ? 0 : -ENOMEM;
}

- if (outcnt > stream->outcnt)
- fa_zero(out, stream->outcnt, (outcnt - stream->outcnt));
-
- stream->out = out;
-
- return 0;
+ return fa_resize(stream->out, outcnt, gfp);
}

static int sctp_stream_alloc_in(struct sctp_stream *stream, __u16 incnt,
gfp_t gfp)
{
- struct flex_array *in;
- size_t elem_size = sizeof(struct sctp_stream_in);
+ if (!stream->in) {
+ stream->in = fa_alloc(sizeof(struct sctp_stream_in),
+ incnt, gfp);

- in = fa_alloc(elem_size, incnt, gfp);
- if (!in)
- return -ENOMEM;
-
- if (stream->in) {
- fa_copy(in, stream->in, 0, min(incnt, stream->incnt));
- fa_free(stream->in);
+ return stream->in ? 0 : -ENOMEM;
}

- if (incnt > stream->incnt)
- fa_zero(in, stream->incnt, (incnt - stream->incnt));
-
- stream->in = in;
-
- return 0;
+ return fa_resize(stream->in, incnt, gfp);
}

int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
--
2.1.0
\
 
 \ /
  Last update: 2018-12-07 07:32    [W:0.094 / U:0.376 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site