From: Yonghong Song <yhs@fb.com>
To: <ast@fb.com>, <daniel@iogearbox.net>, <netdev@vger.kernel.org>
Cc: <kernel-team@fb.com>
Subject: [PATCH bpf-next] bpf: fix sock hashmap kmalloc warning
Date: Wed, 16 May 2018 14:06:26 -0700 [thread overview]
Message-ID: <20180516210626.776403-1-yhs@fb.com> (raw)
syzbot reported a kernel warning below:
WARNING: CPU: 0 PID: 4499 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 4499 Comm: syz-executor050 Not tainted 4.17.0-rc3+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b9/0x294 lib/dump_stack.c:113
panic+0x22f/0x4de kernel/panic.c:184
__warn.cold.8+0x163/0x1b3 kernel/panic.c:536
report_bug+0x252/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:kmalloc_slab+0x56/0x70 mm/slab_common.c:996
RSP: 0018:ffff8801d907fc58 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801aeecb280 RCX: ffffffff8185ebd7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000ffffffe1
RBP: ffff8801d907fc58 R08: ffff8801adb5e1c0 R09: ffffed0035a84700
R10: ffffed0035a84700 R11: ffff8801ad423803 R12: ffff8801aeecb280
R13: 00000000fffffff4 R14: ffff8801ad891a00 R15: 00000000014200c0
__do_kmalloc mm/slab.c:3713 [inline]
__kmalloc+0x25/0x760 mm/slab.c:3727
kmalloc include/linux/slab.h:517 [inline]
map_get_next_key+0x24a/0x640 kernel/bpf/syscall.c:858
__do_sys_bpf kernel/bpf/syscall.c:2131 [inline]
__se_sys_bpf kernel/bpf/syscall.c:2096 [inline]
__x64_sys_bpf+0x354/0x4f0 kernel/bpf/syscall.c:2096
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The test case is against sock hashmap with a key size 0xffffffe1.
Such a large key size will cause the below code in function
sock_hash_alloc() overflowing and produces a smaller elem_size,
hence map creation will be successful.
htab->elem_size = sizeof(struct htab_elem) +
round_up(htab->map.key_size, 8);
Later, when map_get_next_key is called and kernel tries
to allocate the key unsuccessfully, it will issue
the above warning.
Similar to hashtab, ensure the key size is at most
MAX_BPF_STACK for a successful map creation.
Fixes: 81110384441a ("bpf: sockmap, add hash map support")
Reported-by: syzbot+e4566d29080e7f3460ff@syzkaller.appspotmail.com
Signed-off-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/sockmap.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 56879c9fd3a4..79f5e8988889 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -1990,6 +1990,12 @@ static struct bpf_map *sock_hash_alloc(union bpf_attr *attr)
attr->map_flags & ~SOCK_CREATE_FLAG_MASK)
return ERR_PTR(-EINVAL);
+ if (attr->key_size > MAX_BPF_STACK)
+ /* eBPF programs initialize keys on stack, so they cannot be
+ * larger than max stack size
+ */
+ return ERR_PTR(-E2BIG);
+
err = bpf_tcp_ulp_register();
if (err && err != -EEXIST)
return ERR_PTR(err);
--
2.14.3
next reply other threads:[~2018-05-16 21:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-16 21:06 Yonghong Song [this message]
2018-05-16 21:14 ` [PATCH bpf-next] bpf: fix sock hashmap kmalloc warning John Fastabend
2018-05-16 22:58 ` Daniel Borkmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180516210626.776403-1-yhs@fb.com \
--to=yhs@fb.com \
--cc=ast@fb.com \
--cc=daniel@iogearbox.net \
--cc=kernel-team@fb.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.