Hi all,
On Sun, Dec 13, 2020 at 06:53:10AM -0800, syzbot wrote:
> BUG: memory leak
> unreferenced object 0xffff88810f897940 (size 64):
> comm "syz-executor991", pid 8502, jiffies 4294942194 (age 14.080s)
> hex dump (first 32 bytes):
> 7f 00 00 00 80 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 a0 37 0c 81 88 ff ff 00 00 00 00 00 00 00 00 ..7.............
> backtrace:
> [<00000000639d0dd1>] xskq_create+0x23/0xd0 include/linux/slab.h:552
> [<00000000b680b035>] xsk_init_queue net/xdp/xsk.c:508 [inline]
> [<00000000b680b035>] xsk_setsockopt+0x1c4/0x590 net/xdp/xsk.c:875
> [<000000002b302260>] __sys_setsockopt+0x1b0/0x360 net/socket.c:2132
> [<00000000ae03723e>] __do_sys_setsockopt net/socket.c:2143 [inline]
> [<00000000ae03723e>] __se_sys_setsockopt net/socket.c:2140 [inline]
> [<00000000ae03723e>] __x64_sys_setsockopt+0x22/0x30 net/socket.c:2140
> [<0000000005c2b4a0>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> [<0000000003db140f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
I have tested the following diff locally against syzbot's reproducer,
and sent a patch to it [1] for testing. I will send a real patch here
tomorrow if syzbot is happy about it. Please see explanation below.
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -37,6 +37,9 @@ void xp_destroy(struct xsk_buff_pool *pool)
if (!pool)
return;
+ xskq_destroy(pool->fq);
+ xskq_destroy(pool->cq);
+
kvfree(pool->heads);
kvfree(pool);
}
@@ -234,16 +237,6 @@ static void xp_release_deferred(struct work_struct *work)
xp_clear_dev(pool);
rtnl_unlock();
- if (pool->fq) {
- xskq_destroy(pool->fq);
- pool->fq = NULL;
- }
-
- if (pool->cq) {
- xskq_destroy(pool->cq);
- pool->cq = NULL;
- }
-
xdp_put_umem(pool->umem, false);
xp_destroy(pool);
}
When xsk_bind() allocates `xs->pool` but something else goes wrong:
xs->pool = xp_create_and_assign_umem(xs, xs->umem);
[...]
if (err) {
xp_destroy(xs->pool);
xp_destroy() doesn't free `pool->{f,c}q`, causing a memory leak. Move
`xskq_destroy(pool->{f,c}q)` from xp_release_deferred() to xp_destroy().
Also, since xskq_destroy() already does null check, I think it's
unnecessary to do it again here?
Thanks,
Peilin Ye
[1] https://syzkaller.appspot.com/bug?id=fea808dfe3c6dfdd6ba9778becbffe0b14e91294
