Re: [PATCH v2 1/2] powerpc: Fix virt_addr_valid() check
From: Christophe Leroy <hidden>
Date: 2022-01-10 08:03:21
Also in:
linux-mm, lkml
Le 25/12/2021 à 13:06, Kefeng Wang a écrit :
When run ethtool eth0, the BUG occurred,
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
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.
As commit 4dd7554a6456 ("powerpc/64: Add VIRTUAL_BUG_ON checks for __va
and __pa addresses") does, make sure the virt addr above PAGE_OFFSET in
the virt_addr_valid().The change done by that commit only applies to PPC64. The change you are doing applies to both PPC64 and PPC32. Did you verify the impact (or should I say the absence of impact) on PPC32 ?
quoted hunk ↗ jump to hunk
Signed-off-by: Kefeng Wang <redacted> --- arch/powerpc/include/asm/page.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h index 254687258f42..300d4c105a3a 100644 --- a/arch/powerpc/include/asm/page.h +++ b/arch/powerpc/include/asm/page.h@@ -132,7 +132,10 @@ static inline bool pfn_valid(unsigned long pfn) #define virt_to_page(kaddr) pfn_to_page(virt_to_pfn(kaddr)) #define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT) -#define virt_addr_valid(kaddr) pfn_valid(virt_to_pfn(kaddr)) +#define virt_addr_valid(vaddr) ({ \ + unsigned long _addr = (unsigned long)vaddr; \ + (unsigned long)(_addr) >= PAGE_OFFSET && pfn_valid(virt_to_pfn(_addr)); \
_addr is already an 'unsigned long' so you shouldnt need to cast it.
+}) /* * On Book-E parts we need __va to parse the device tree and we can't