NACK: [SRU][J][PATCH v2 1/1] ARM: 9359/1: flush: check if the folio is reserved for no-mapping addresses

[Koichiro Den]

On Mon, Sep 30, 2024 at 12:04:23PM +0900, Koichiro Den wrote:
> From: Yongqiang Liu <liuyongqiang13 at huawei.com>
> 
> Since commit a4d5613c4dc6 ("arm: extend pfn_valid to take into account
> freed memory map alignment") changes the semantics of pfn_valid() to check
> presence of the memory map for a PFN. A valid page for an address which
> is reserved but not mapped by the kernel[1], the system crashed during
> some uio test with the following memory layout:
> 
>  node   0: [mem 0x00000000c0a00000-0x00000000cc8fffff]
>  node   0: [mem 0x00000000d0000000-0x00000000da1fffff]
>  the uio layout is：0xc0900000, 0x100000
> 
> the crash backtrace like:
> 
>   Unable to handle kernel paging request at virtual address bff00000
>   [...]
>   CPU: 1 PID: 465 Comm: startapp.bin Tainted: G           O      5.10.0 #1
>   Hardware name: Generic DT based system
>   PC is at b15_flush_kern_dcache_area+0x24/0x3c
>   LR is at __sync_icache_dcache+0x6c/0x98
>   [...]
>    (b15_flush_kern_dcache_area) from (__sync_icache_dcache+0x6c/0x98)
>    (__sync_icache_dcache) from (set_pte_at+0x28/0x54)
>    (set_pte_at) from (remap_pfn_range+0x1a0/0x274)
>    (remap_pfn_range) from (uio_mmap+0x184/0x1b8 [uio])
>    (uio_mmap [uio]) from (__mmap_region+0x264/0x5f4)
>    (__mmap_region) from (__do_mmap_mm+0x3ec/0x440)
>    (__do_mmap_mm) from (do_mmap+0x50/0x58)
>    (do_mmap) from (vm_mmap_pgoff+0xfc/0x188)
>    (vm_mmap_pgoff) from (ksys_mmap_pgoff+0xac/0xc4)
>    (ksys_mmap_pgoff) from (ret_fast_syscall+0x0/0x5c)
>   Code: e0801001 e2423001 e1c00003 f57ff04f (ee070f3e)
>   ---[ end trace 09cf0734c3805d52 ]---
>   Kernel panic - not syncing: Fatal exception
> 
> So check if PG_reserved was set to solve this issue.
> 
> [1]: https://lore.kernel.org/lkml/Zbtdue57RO0QScJM@linux.ibm.com/
> 
> Fixes: a4d5613c4dc6 ("arm: extend pfn_valid to take into account freed memory map alignment")
> Suggested-by: Mike Rapoport <rppt at linux.ibm.com>
> Signed-off-by: Yongqiang Liu <liuyongqiang13 at huawei.com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> (backported from commit 0c66c6f4e21cb22220cbd8821c5c73fc157d20dc)
> [koichiroden: folio_test_reserved replaced by PageReserved due to
>  missing commit 8b5989f33337 ("arm: implement the new page table range
>  API"). folio conversion is not backported in general, so notice that
>  even d389a4a81155 ("mm: Add folio flag manipulation functions") does
>  not exist in Xenial]

s/Xenial/Jammy/

> CVE-2024-26947
> Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
> ---
>  arch/arm/mm/flush.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
> index 7ff9feea13a6..b19ecc307ad4 100644
> --- a/arch/arm/mm/flush.c
> +++ b/arch/arm/mm/flush.c
> @@ -280,6 +280,8 @@ void __sync_icache_dcache(pte_t pteval)
>  		return;
>  
>  	page = pfn_to_page(pfn);
> +	if (PageReserved(page))
> +		return;
>  	if (cache_is_vipt_aliasing())
>  		mapping = page_mapping_file(page);
>  	else
> -- 
> 2.43.0
>