linux-kernel - Re: [PATCH v5] MIPS: mm: kmalloc tlb

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] [day] [month] [year] [list]

Message-ID: <aSrqNv5xupUXLo6d@alpha.franken.de>
Date: Sat, 29 Nov 2025 13:42:30 +0100
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: "Maciej W. Rozycki" <macro@...am.me.uk>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>,
	Gregory CLEMENT <gregory.clement@...tlin.com>,
	linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] MIPS: mm: kmalloc tlb_vpn array to avoid stack
 overflow

On Fri, Nov 28, 2025 at 04:53:46PM +0000, Maciej W. Rozycki wrote:
> From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> 
> Owing to Config4.MMUSizeExt and VTLB/FTLB MMU features later MIPSr2+ 
> cores can have more than 64 TLB entries.  Therefore allocate an array 
> for uniquification instead of placing too small an array on the stack.
> 
> Fixes: 35ad7e181541 ("MIPS: mm: tlb-r4k: Uniquify TLB entries on init")
> Co-developed-by: Maciej W. Rozycki <macro@...am.me.uk>
> Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
> Signed-off-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: stable@...r.kernel.org # v6.17+: 9f048fa48740: MIPS: mm: Prevent a TLB shutdown on initial uniquification
> Cc: stable@...r.kernel.org # v6.17+
> ---
>  Verified with Malta/74Kf and Malta/interAptiv for initial and secondary 
> CPU bootstrap.  The PM path hasn't been covered, but is expected to be 
> the same as secondary CPU bootstrap.
> 
>  NB Malta/interAptiv has issues later on in SMP boot (boots fine UP) and 
> hangs with repeated:
> 
> irq 23: nobody cared (try booting with the "irqpoll" option)
> CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.18.0-rc1-dirty #2 NONE
> 
> messages (for the CP0 timer interrupt AFAICT; GIC timer is supposed to 
> be used instead).  This will have to be bisected.
> 
> Changes from v4:
> 
> - Mark `r4k_tlb_uniquify' `__ref' so as to silence `modpost'.
> 
> Changes from v3:
> 
> - Rearrange tags including stable backport ones so as to pick the original 
>   change together with this fix only.
> 
> Changes from v2:
> 
> - Use the bootmem allocator for early calls (CPU #0 bootstrap).
> 
> - Update the change description; mark for stable backporting.
> ---
>  arch/mips/mm/tlb-r4k.c |   18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)

applied to mips-fixes.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]