netdev - Re: [PATCH v10 1/2] net/bnx2x: Prevent access to a freed page in page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e3bdd081-8c81-4c23-b822-091d3f122afa@intel.com>
Date: Wed, 14 Feb 2024 12:47:15 -0800
From: Jacob Keller <jacob.e.keller@...el.com>
To: Thinh Tran <thinhtr@...ux.vnet.ibm.com>, <kuba@...nel.org>
CC: <netdev@...r.kernel.org>, <davem@...emloft.net>, <manishc@...vell.com>,
	<pabeni@...hat.com>, <skalluru@...vell.com>, <simon.horman@...igine.com>,
	<edumazet@...gle.com>, <VENKATA.SAI.DUGGI@....com>, <drc@...ux.vnet.ibm.com>,
	<abdhalee@...ibm.com>
Subject: Re: [PATCH v10 1/2] net/bnx2x: Prevent access to a freed page in
 page_pool



On 2/13/2024 10:32 AM, Thinh Tran wrote:
> Fix race condition leading to system crash during EEH error handling
> 
> During EEH error recovery, the bnx2x driver's transmit timeout logic
> could cause a race condition when handling reset tasks. The
> bnx2x_tx_timeout() schedules reset tasks via bnx2x_sp_rtnl_task(),
> which ultimately leads to bnx2x_nic_unload(). In bnx2x_nic_unload()
> SGEs are freed using bnx2x_free_rx_sge_range(). However, this could
> overlap with the EEH driver's attempt to reset the device using
> bnx2x_io_slot_reset(), which also frees SGEs. This race condition can
> result in system crashes due to accessing freed memory locations.
> 
> [  793.003930] EEH: Beginning: 'slot_reset'
> [  793.003937] PCI 0011:01:00.0#10000: EEH: Invoking bnx2x->slot_reset()
> [  793.003939] bnx2x: [bnx2x_io_slot_reset:14228(eth1)]IO slot reset initializing...
> [  793.004037] bnx2x 0011:01:00.0: enabling device (0140 -> 0142)
> [  793.008839] bnx2x: [bnx2x_io_slot_reset:14244(eth1)]IO slot reset --> driver unload
> [  793.122134] Kernel attempted to read user page (0) - exploit attempt? (uid: 0)
> [  793.122143] BUG: Kernel NULL pointer dereference on read at 0x00000000
> [  793.122147] Faulting instruction address: 0xc0080000025065fc
> [  793.122152] Oops: Kernel access of bad area, sig: 11 [#1]
> .....
> [  793.122315] Call Trace:
> [  793.122318] [c000000003c67a20] [c00800000250658c] bnx2x_io_slot_reset+0x204/0x610 [bnx2x] (unreliable)
> [  793.122331] [c000000003c67af0] [c0000000000518a8] eeh_report_reset+0xb8/0xf0
> [  793.122338] [c000000003c67b60] [c000000000052130] eeh_pe_report+0x180/0x550
> [  793.122342] [c000000003c67c70] [c00000000005318c] eeh_handle_normal_event+0x84c/0xa60
> [  793.122347] [c000000003c67d50] [c000000000053a84] eeh_event_handler+0xf4/0x170
> [  793.122352] [c000000003c67da0] [c000000000194c58] kthread+0x1c8/0x1d0
> [  793.122356] [c000000003c67e10] [c00000000000cf64] ret_from_kernel_thread+0x5c/0x64
> 
> To solve this issue, we need to verify page pool allocations before
> freeing.
> 
> Fixes: 4cace675d687 ("bnx2x: Alloc 4k fragment for each rx ring buffer element")
> 
> Signed-off-by: Thinh Tran <thinhtr@...ux.vnet.ibm.com>
> 
> 
> ---
>  drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h
> index d8b1824c334d..0bc1367fd649 100644
> --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h
> +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h
> @@ -1002,9 +1002,6 @@ static inline void bnx2x_set_fw_mac_addr(__le16 *fw_hi, __le16 *fw_mid,
>  static inline void bnx2x_free_rx_mem_pool(struct bnx2x *bp,
>  					  struct bnx2x_alloc_pool *pool)
>  {
> -	if (!pool->page)
> -		return;
> -
>  	put_page(pool->page);
>  
>  	pool->page = NULL;
> @@ -1015,6 +1012,9 @@ static inline void bnx2x_free_rx_sge_range(struct bnx2x *bp,
>  {
>  	int i;
>  
> +	if (!fp->page_pool.page)
> +		return;
> +

Doesn't this still leave a race window where put_page was already called
but page hasn't yet been set NULL? I think you either need to assign
NULL first (and possibly WRITE_ONCE or a barrier depending on platform?)
or some other serialization mechanism to ensure only one thread runs here?

I guess the issue you're seeing is that bnx2x_free_rx_sge_range calls
bnx2x_free_rx_sge even if the page was already removed? Does that mean
you already have some other serialization ensuring that you can't have
both threads call put_page simultaneously?

>  	if (fp->mode == TPA_MODE_DISABLED)
>  		return;
>