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

[Koichiro Den]

On Mon, Sep 23, 2024 at 02:35:59PM +0200, Thibault Ferrante wrote:
> On 11-09-2024 03:53, 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: Adjusted context due to missing commits:
> You dhould also mention the code change, maybe something like :
> folio_test_reserved replaced by PageReserved due to missing commit:
>   XXXXXX

Thanks for reviewing. I'll shortly send v2.

> >   8b5989f33337 ("arm: implement the new page table range API")
> >   d389a4a81155 ("mm: Add folio flag manipulation functions")]
> 
> > 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 6d89db7895d1..8ce681d76665 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
> 
> 
> -- 
> --
> Thibault
> 
> -- 
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