RE: [PATCH v3] nfp: fix use-after-free in area_cache_get()

[Yinjun Zhang]

On Wed, 10 Aug 2022 15:30:57 +0800 Jialiang Wang wrote:
> area_cache_get() is used to distribute cache->area and set cache->id,
>  and if cache->id is not 0 and cache->area->kref refcount is 0, it will
>  release the cache->area by nfp_cpp_area_release(). area_cache_get()
>  set cache->id before cpp->op->area_init() and nfp_cpp_area_acquire().
> 
> But if area_init() or nfp_cpp_area_acquire() fails, the cache->id is
>  is already set but the refcount is not increased as expected. At this
>  time, calling the nfp_cpp_area_release() will cause use-after-free.
> 
> To avoid the use-after-free, set cache->id after area_init() and
>  nfp_cpp_area_acquire() complete successfully.
> 
> Note: This vulnerability is triggerable by providing emulated device
>  equipped with specified configuration.
> 
>  BUG: KASAN: use-after-free in nfp6000_area_init (/home/user/Kernel/v5.19
> /x86_64/src/drivers/net/ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c:7
> 60)
>   Write of size 4 at addr ffff888005b7f4a0 by task swapper/0/1
> 
>  Call Trace:
>   <TASK>
>  nfp6000_area_init (/home/user/Kernel/v5.19/x86_64/src/drivers/net
> /ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c:760)
>  area_cache_get.constprop.8 (/home/user/Kernel/v5.19/x86_64/src/drivers
> /net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c:884)
> 
>  Allocated by task 1:
>  nfp_cpp_area_alloc_with_name
> (/home/user/Kernel/v5.19/x86_64/src/drivers
> /net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c:303)
>  nfp_cpp_area_cache_add
> (/home/user/Kernel/v5.19/x86_64/src/drivers/net
> /ethernet/netronome/nfp/nfpcore/nfp_cppcore.c:802)
>  nfp6000_init (/home/user/Kernel/v5.19/x86_64/src/drivers/net/ethernet
> /netronome/nfp/nfpcore/nfp6000_pcie.c:1230)
>  nfp_cpp_from_operations
> (/home/user/Kernel/v5.19/x86_64/src/drivers/net
> /ethernet/netronome/nfp/nfpcore/nfp_cppcore.c:1215)
>  nfp_pci_probe (/home/user/Kernel/v5.19/x86_64/src/drivers/net/ethernet
> /netronome/nfp/nfp_main.c:744)
> 
>  Freed by task 1:
>  kfree (/home/user/Kernel/v5.19/x86_64/src/mm/slub.c:4562)
>  area_cache_get.constprop.8 (/home/user/Kernel/v5.19/x86_64/src/drivers
> /net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c:873)
>  nfp_cpp_read (/home/user/Kernel/v5.19/x86_64/src/drivers/net/ethernet
> /netronome/nfp/nfpcore/nfp_cppcore.c:924
> /home/user/Kernel/v5.19/x86_64
> /src/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c:973)
>  nfp_cpp_readl (/home/user/Kernel/v5.19/x86_64/src/drivers/net/ethernet
> /netronome/nfp/nfpcore/nfp_cpplib.c:48)
> 
> Signed-off-by: Jialiang Wang <wangjialiang0806@xxxxxxx>

Thanks.
Reviewed-by: Yinjun Zhang <yinjun.zhang@xxxxxxxxxxxx>