Messages in this thread Patch in this message | | | Date | Fri, 24 Dec 2021 15:06:25 +0800 | Subject | Re: [PATCH] Revert "mm/usercopy: Drop extra is_vmalloc_or_module() check" | From | Kefeng Wang <> |
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On 2021/12/24 14:01, Christophe Leroy wrote: > > 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.
Our product reports this bug to me, after let them do some test,
I found virt_addr_valid return true for vmalloc'ed memory on their board.
I think DEBUG_VIRTUAL could not be work well too, but I can't test it.
> > 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()")
Yes, I check the history, fix virt_addr_valid() on PowerPC is what I firstly want to do,
but I am not familiar with PPC, and also HARDENED_USERCOPY on other's ARCHs could
has this issue too, so I add the workaround back.
1) PPC maintainer/expert, any suggestion ?
2) Maybe we could add some check to WARN this scenario.
--- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -229,6 +229,8 @@ static inline void check_heap_object(const void *ptr, unsigned long n, if (!virt_addr_valid(ptr)) return;
+ WARN_ON_ONCE(is_vmalloc_or_module_addr(ptr));
> In the meantime, can you provide more information on your config, > especially which memory model is used ?
Some useful configs,
CONFIG_PPC64=y CONFIG_PPC_BOOK3E_64=y CONFIG_E5500_CPU=y CONFIG_TARGET_CPU_BOOL=y CONFIG_PPC_BOOK3E=y CONFIG_E500=y CONFIG_PPC_E500MC=y CONFIG_PPC_FPU=y CONFIG_FSL_EMB_PERFMON=y CONFIG_FSL_EMB_PERF_EVENT=y CONFIG_FSL_EMB_PERF_EVENT_E500=y CONFIG_BOOKE=y CONFIG_PPC_FSL_BOOK3E=y CONFIG_PTE_64BIT=y CONFIG_PHYS_64BIT=y CONFIG_PPC_MMU_NOHASH=y CONFIG_PPC_BOOK3E_MMU=y CONFIG_SELECT_MEMORY_MODEL=y CONFIG_FLATMEM_MANUAL=y CONFIG_FLATMEM=y CONFIG_FLAT_NODE_MEM_MAP=y CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y > > Christophe
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