From patchwork Fri Nov 15 12:53:47 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Maciej Fijalkowski X-Patchwork-Id: 13876199 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A83DC1BCA19; Fri, 15 Nov 2024 12:54:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731675242; cv=none; b=bQQGCWSR+cEUJwuqa4Rzr7ZYT16w1ibImEmacsyU6tNhq/4c9p0Fjz3XBgB6biRphdZnXgQ+uvC3UErteMaXNV66DBI26l0wP8QXv7BcnvWRcwg7mr4YOaGx7XEPikNrvnYZSUY3qDpFfjwh6NtA6Q1OFIqvzn0wCJG84+Xn1i8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731675242; c=relaxed/simple; bh=5gLwRkHtra4mGAlh8DUhPfiM3IoHF+mWNPxUInl0EX0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=sWXQk48AygiEHbwGP3HLwukMY87mpYFSRphwPXTTCzZBkgk3bwhC+Evmv2Ljk6LzdRUAkNMBgGEVL0Th2Lvc48ULc0FSUZoUnzMJyAaTpjJoBQXaot5fzkvVxZBWUF5wVpX3wYF19sg2zEK1F7vv5iojNKpAntJCqXbY4nJRYnY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=jOapYzWi; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="jOapYzWi" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1731675241; x=1763211241; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=5gLwRkHtra4mGAlh8DUhPfiM3IoHF+mWNPxUInl0EX0=; b=jOapYzWieXxA0rvPgiHhVwqpFMJF21vWITEDpJkKjs3bHV9h95HaF0P3 lPA1jHCYohOZ8ADUlTqz2msRclUiluJ2pWmTJhReWBak8dGcvy952pL1m NPPfxI4hKWxWptaPiEWBgc5VVb16OHi81bJd7mau83cy+jbbA15QAbDJj In4FZkBh4OuSao2FelaW8sb13KN9Qcg5NDPRwugMx7AnP8asUhzcar08J J5XP/tccEIm9b8PnTxBBNCDuVE4BMmqe2ovvBTMOa5cksOgpEvaScEfRF WJ9u/R5itvpmDeljOabpnZ7lPwQM5gxfvBzstIKTG0ot96a7YRq9ZPTdZ Q==; X-CSE-ConnectionGUID: 7RvZupg4QECznYiX6uXNXQ== X-CSE-MsgGUID: kQmlDM62QYSGZ5YT88OadQ== X-IronPort-AV: E=McAfee;i="6700,10204,11257"; a="35607632" X-IronPort-AV: E=Sophos;i="6.12,156,1728975600"; d="scan'208";a="35607632" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2024 04:54:00 -0800 X-CSE-ConnectionGUID: pPFwgR3TT1WgqDYAoWAE5w== X-CSE-MsgGUID: jBd7WpgJSBOt88dreyBQwA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,156,1728975600"; d="scan'208";a="88555497" Received: from boxer.igk.intel.com ([10.102.20.173]) by orviesa009.jf.intel.com with ESMTP; 15 Nov 2024 04:53:57 -0800 From: Maciej Fijalkowski To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org Cc: netdev@vger.kernel.org, magnus.karlsson@intel.com, bjorn@kernel.org, maciej.fijalkowski@intel.com, jordyzomer@google.com, security@kernel.org Subject: [PATCH bpf 1/2] xsk: fix OOB map writes when deleting elements Date: Fri, 15 Nov 2024 13:53:47 +0100 Message-Id: <20241115125348.654145-2-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20241115125348.654145-1-maciej.fijalkowski@intel.com> References: <20241115125348.654145-1-maciej.fijalkowski@intel.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Jordy says: " In the xsk_map_delete_elem function an unsigned integer (map->max_entries) is compared with a user-controlled signed integer (k). Due to implicit type conversion, a large unsigned value for map->max_entries can bypass the intended bounds check: if (k >= map->max_entries) return -EINVAL; This allows k to hold a negative value (between -2147483648 and -2), which is then used as an array index in m->xsk_map[k], which results in an out-of-bounds access. spin_lock_bh(&m->lock); map_entry = &m->xsk_map[k]; // Out-of-bounds map_entry old_xs = unrcu_pointer(xchg(map_entry, NULL)); // Oob write if (old_xs) xsk_map_sock_delete(old_xs, map_entry); spin_unlock_bh(&m->lock); The xchg operation can then be used to cause an out-of-bounds write. Moreover, the invalid map_entry passed to xsk_map_sock_delete can lead to further memory corruption. " It indeed results in following splat: [76612.897343] BUG: unable to handle page fault for address: ffffc8fc2e461108 [76612.904330] #PF: supervisor write access in kernel mode [76612.909639] #PF: error_code(0x0002) - not-present page [76612.914855] PGD 0 P4D 0 [76612.917431] Oops: Oops: 0002 [#1] PREEMPT SMP [76612.921859] CPU: 11 UID: 0 PID: 10318 Comm: a.out Not tainted 6.12.0-rc1+ #470 [76612.929189] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 [76612.939781] RIP: 0010:xsk_map_delete_elem+0x2d/0x60 [76612.944738] Code: 00 00 41 54 55 53 48 63 2e 3b 6f 24 73 38 4c 8d a7 f8 00 00 00 48 89 fb 4c 89 e7 e8 2d bf 05 00 48 8d b4 eb 00 01 00 00 31 ff <48> 87 3e 48 85 ff 74 05 e8 16 ff ff ff 4c 89 e7 e8 3e bc 05 00 31 [76612.963774] RSP: 0018:ffffc9002e407df8 EFLAGS: 00010246 [76612.969079] RAX: 0000000000000000 RBX: ffffc9002e461000 RCX: 0000000000000000 [76612.976323] RDX: 0000000000000001 RSI: ffffc8fc2e461108 RDI: 0000000000000000 [76612.983569] RBP: ffffffff80000001 R08: 0000000000000000 R09: 0000000000000007 [76612.990812] R10: ffffc9002e407e18 R11: ffff888108a38858 R12: ffffc9002e4610f8 [76612.998060] R13: ffff888108a38858 R14: 00007ffd1ae0ac78 R15: ffffc9002e4610c0 [76613.005303] FS: 00007f80b6f59740(0000) GS:ffff8897e0ec0000(0000) knlGS:0000000000000000 [76613.013517] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [76613.019349] CR2: ffffc8fc2e461108 CR3: 000000011e3ef001 CR4: 00000000007726f0 [76613.026595] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [76613.033841] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [76613.041086] PKRU: 55555554 [76613.043842] Call Trace: [76613.046331] [76613.048468] ? __die+0x20/0x60 [76613.051581] ? page_fault_oops+0x15a/0x450 [76613.055747] ? search_extable+0x22/0x30 [76613.059649] ? search_bpf_extables+0x5f/0x80 [76613.063988] ? exc_page_fault+0xa9/0x140 [76613.067975] ? asm_exc_page_fault+0x22/0x30 [76613.072229] ? xsk_map_delete_elem+0x2d/0x60 [76613.076573] ? xsk_map_delete_elem+0x23/0x60 [76613.080914] __sys_bpf+0x19b7/0x23c0 [76613.084555] __x64_sys_bpf+0x1a/0x20 [76613.088194] do_syscall_64+0x37/0xb0 [76613.091832] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [76613.096962] RIP: 0033:0x7f80b6d1e88d [76613.100592] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 73 b5 0f 00 f7 d8 64 89 01 48 [76613.119631] RSP: 002b:00007ffd1ae0ac68 EFLAGS: 00000206 ORIG_RAX: 0000000000000141 [76613.131330] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f80b6d1e88d [76613.142632] RDX: 0000000000000098 RSI: 00007ffd1ae0ad20 RDI: 0000000000000003 [76613.153967] RBP: 00007ffd1ae0adc0 R08: 0000000000000000 R09: 0000000000000000 [76613.166030] R10: 00007f80b6f77040 R11: 0000000000000206 R12: 00007ffd1ae0aed8 [76613.177130] R13: 000055ddf42ce1e9 R14: 000055ddf42d0d98 R15: 00007f80b6fab040 [76613.188129] Fix this by simply changing key type from int to u32. Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP") Reported-by: Jordy Zomer Suggested-by: Jordy Zomer Signed-off-by: Maciej Fijalkowski Reviewed-by: Toke Høiland-Jørgensen --- net/xdp/xskmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c index e1c526f97ce3..afa457506274 100644 --- a/net/xdp/xskmap.c +++ b/net/xdp/xskmap.c @@ -224,7 +224,7 @@ static long xsk_map_delete_elem(struct bpf_map *map, void *key) struct xsk_map *m = container_of(map, struct xsk_map, map); struct xdp_sock __rcu **map_entry; struct xdp_sock *old_xs; - int k = *(u32 *)key; + u32 k = *(u32 *)key; if (k >= map->max_entries) return -EINVAL;