Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753361AbdHRNix (ORCPT ); Fri, 18 Aug 2017 09:38:53 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55460 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752767AbdHRNPr (ORCPT ); Fri, 18 Aug 2017 09:15:47 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Brian Norris" , "Kalle Valo" Date: Fri, 18 Aug 2017 14:13:20 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 068/134] mwifiex: pcie: fix cmd_buf use-after-free in remove/reset In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6599 Lines: 143 3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Brian Norris commit 3c8cb9ad032d737b874e402c59eb51e3c991a144 upstream. Command buffers (skb's) are allocated by the main driver, and freed upon the last use. That last use is often in mwifiex_free_cmd_buffer(). In the meantime, if the command buffer gets used by the PCI driver, we map it as DMA-able, and store the mapping information in the 'cb' memory. However, if a command was in-flight when resetting the device (and therefore was still mapped), we don't get a chance to unmap this memory until after the core has cleaned up its command handling. Let's keep a refcount within the PCI driver, so we ensure the memory only gets freed after we've finished unmapping it. Noticed by KASAN when forcing a reset via: echo 1 > /sys/bus/pci/.../reset The same code path can presumably be exercised in remove() and shutdown(). [ 205.390377] mwifiex_pcie 0000:01:00.0: info: shutdown mwifiex... [ 205.400393] ================================================================== [ 205.407719] BUG: KASAN: use-after-free in mwifiex_unmap_pci_memory.isra.14+0x4c/0x100 [mwifiex_pcie] at addr ffffffc0ad471b28 [ 205.419040] Read of size 16 by task bash/1913 [ 205.423421] ============================================================================= [ 205.431625] BUG skbuff_head_cache (Tainted: G B ): kasan: bad access detected [ 205.439815] ----------------------------------------------------------------------------- [ 205.439815] [ 205.449534] INFO: Allocated in __build_skb+0x48/0x114 age=1311 cpu=4 pid=1913 [ 205.456709] alloc_debug_processing+0x124/0x178 [ 205.461282] ___slab_alloc.constprop.58+0x528/0x608 [ 205.466196] __slab_alloc.isra.54.constprop.57+0x44/0x54 [ 205.471542] kmem_cache_alloc+0xcc/0x278 [ 205.475497] __build_skb+0x48/0x114 [ 205.479019] __netdev_alloc_skb+0xe0/0x170 [ 205.483244] mwifiex_alloc_cmd_buffer+0x68/0xdc [mwifiex] [ 205.488759] mwifiex_init_fw+0x40/0x6cc [mwifiex] [ 205.493584] _mwifiex_fw_dpc+0x158/0x520 [mwifiex] [ 205.498491] mwifiex_reinit_sw+0x2c4/0x398 [mwifiex] [ 205.503510] mwifiex_pcie_reset_notify+0x114/0x15c [mwifiex_pcie] [ 205.509643] pci_reset_notify+0x5c/0x6c [ 205.513519] pci_reset_function+0x6c/0x7c [ 205.517567] reset_store+0x68/0x98 [ 205.521003] dev_attr_store+0x54/0x60 [ 205.524705] sysfs_kf_write+0x9c/0xb0 [ 205.528413] INFO: Freed in __kfree_skb+0xb0/0xbc age=131 cpu=4 pid=1913 [ 205.535064] free_debug_processing+0x264/0x370 [ 205.539550] __slab_free+0x84/0x40c [ 205.543075] kmem_cache_free+0x1c8/0x2a0 [ 205.547030] __kfree_skb+0xb0/0xbc [ 205.550465] consume_skb+0x164/0x178 [ 205.554079] __dev_kfree_skb_any+0x58/0x64 [ 205.558304] mwifiex_free_cmd_buffer+0xa0/0x158 [mwifiex] [ 205.563817] mwifiex_shutdown_drv+0x578/0x5c4 [mwifiex] [ 205.569164] mwifiex_shutdown_sw+0x178/0x310 [mwifiex] [ 205.574353] mwifiex_pcie_reset_notify+0xd4/0x15c [mwifiex_pcie] [ 205.580398] pci_reset_notify+0x5c/0x6c [ 205.584274] pci_dev_save_and_disable+0x24/0x6c [ 205.588837] pci_reset_function+0x30/0x7c [ 205.592885] reset_store+0x68/0x98 [ 205.596324] dev_attr_store+0x54/0x60 [ 205.600017] sysfs_kf_write+0x9c/0xb0 ... [ 205.800488] Call trace: [ 205.802980] [] dump_backtrace+0x0/0x190 [ 205.808415] [] show_stack+0x20/0x28 [ 205.813506] [] dump_stack+0xa4/0xcc [ 205.818598] [] print_trailer+0x158/0x168 [ 205.824120] [] object_err+0x4c/0x5c [ 205.829210] [] kasan_report+0x334/0x500 [ 205.834641] [] check_memory_region+0x20/0x14c [ 205.840593] [] __asan_loadN+0x14/0x1c [ 205.845879] [] mwifiex_unmap_pci_memory.isra.14+0x4c/0x100 [mwifiex_pcie] [ 205.854282] [] mwifiex_pcie_delete_cmdrsp_buf+0x94/0xa8 [mwifiex_pcie] [ 205.862421] [] mwifiex_pcie_free_buffers+0x11c/0x158 [mwifiex_pcie] [ 205.870302] [] mwifiex_pcie_down_dev+0x70/0x80 [mwifiex_pcie] [ 205.877736] [] mwifiex_shutdown_sw+0x190/0x310 [mwifiex] [ 205.884658] [] mwifiex_pcie_reset_notify+0xd4/0x15c [mwifiex_pcie] [ 205.892446] [] pci_reset_notify+0x5c/0x6c [ 205.898048] [] pci_dev_save_and_disable+0x24/0x6c [ 205.904350] [] pci_reset_function+0x30/0x7c [ 205.910134] [] reset_store+0x68/0x98 [ 205.915312] [] dev_attr_store+0x54/0x60 [ 205.920750] [] sysfs_kf_write+0x9c/0xb0 [ 205.926182] [] kernfs_fop_write+0x184/0x1f8 [ 205.931963] [] __vfs_write+0x6c/0x17c [ 205.937221] [] vfs_write+0xf0/0x1c4 [ 205.942310] [] SyS_write+0x78/0xd8 [ 205.947312] [] el0_svc_naked+0x24/0x28 ... [ 205.998268] ================================================================== This bug has been around in different forms for a while. It was sort of noticed in commit 955ab095c51a ("mwifiex: Do not kfree cmd buf while unregistering PCIe"), but it just fixed the double-free, without acknowledging the potential for use-after-free. Fixes: fc3314609047 ("mwifiex: use pci_alloc/free_consistent APIs for PCIe") Signed-off-by: Brian Norris Signed-off-by: Kalle Valo [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings --- drivers/net/wireless/mwifiex/pcie.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/net/wireless/mwifiex/pcie.c +++ b/drivers/net/wireless/mwifiex/pcie.c @@ -905,6 +905,7 @@ static int mwifiex_pcie_delete_cmdrsp_bu if (card && card->cmd_buf) { mwifiex_unmap_pci_memory(adapter, card->cmd_buf, PCI_DMA_TODEVICE); + dev_kfree_skb_any(card->cmd_buf); } return 0; } @@ -1446,6 +1447,11 @@ mwifiex_pcie_send_cmd(struct mwifiex_ada return -1; card->cmd_buf = skb; + /* + * Need to keep a reference, since core driver might free up this + * buffer before we've unmapped it. + */ + skb_get(skb); /* To send a command, the driver will: 1. Write the 64bit physical address of the data buffer to @@ -1542,6 +1548,7 @@ static int mwifiex_pcie_process_cmd_comp if (card->cmd_buf) { mwifiex_unmap_pci_memory(adapter, card->cmd_buf, PCI_DMA_TODEVICE); + dev_kfree_skb_any(card->cmd_buf); card->cmd_buf = NULL; }