Le 23/12/2021 à 11:21, Kefeng Wang a écrit :
> This reverts commit 517e1fbeb65f5eade8d14f46ac365db6c75aea9b.
>
> usercopy: Kernel memory exposure attempt detected from SLUB object not in SLUB page?! (offset 0, size 1048)!
> kernel BUG at mm/usercopy.c:99
> ...
> usercopy_abort+0x64/0xa0 (unreliable)
> __check_heap_object+0x168/0x190
> __check_object_size+0x1a0/0x200
> dev_ethtool+0x2494/0x2b20
> dev_ioctl+0x5d0/0x770
> sock_do_ioctl+0xf0/0x1d0
> sock_ioctl+0x3ec/0x5a0
> __se_sys_ioctl+0xf0/0x160
> system_call_exception+0xfc/0x1f0
> system_call_common+0xf8/0x200
>
> When run ethtool eth0, the BUG occurred, the code shows below,
>
> data = vzalloc(array_size(gstrings.len, ETH_GSTRING_LEN));
> copy_to_user(useraddr, data, gstrings.len * ETH_GSTRING_LEN))
>
> The data is alloced by vmalloc(), virt_addr_valid(ptr) will return true
> on PowerPC64, which leads to the panic, add back the is_vmalloc_or_module()
> check to fix it.
Is it expected that virt_addr_valid() returns true on PPC64 for
vmalloc'ed memory ? If that's the case it also means that
CONFIG_DEBUG_VIRTUAL won't work as expected either.
If it is unexpected, I think you should fix PPC64 instead of adding this
hack back. Maybe the ARM64 fix can be used as a starting point, see
commit 68dd8ef32162 ("arm64: memory: Fix virt_addr_valid() using
__is_lm_address()")
In the meantime, can you provide more information on your config,
especially which memory model is used ?
Christophe
