6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook kees@kernel.org
[ Upstream commit 8c860ed825cb85f6672cd7b10a8f33e3498a7c81 ]
When reworking the range checking for get_user(), the get_user_8() case on 32-bit wasn't zeroing the high register. (The jump to bad_get_user_8 was accidentally dropped.) Restore the correct error handling destination (and rename the jump to using the expected ".L" prefix).
While here, switch to using a named argument ("size") for the call template ("%c4" to "%c[size]") as already used in the other call templates in this file.
Found after moving the usercopy selftests to KUnit:
# usercopy_test_invalid: EXPECTATION FAILED at lib/usercopy_kunit.c:278 Expected val_u64 == 0, but val_u64 == -60129542144 (0xfffffff200000000)
Closes: https://lore.kernel.org/all/CABVgOSn=tb=Lj9SxHuT4_9MTjjKVxsq-ikdXC4kGHO4CfKV... Fixes: b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()") Reported-by: David Gow davidgow@google.com Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Dave Hansen dave.hansen@linux.intel.com Reviewed-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Reviewed-by: Qiuxu Zhuo qiuxu.zhuo@intel.com Tested-by: David Gow davidgow@google.com Link: https://lore.kernel.org/all/20240610210213.work.143-kees%40kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/include/asm/uaccess.h | 4 ++-- arch/x86/lib/getuser.S | 6 +++++- 2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 0f9bab92a43d7..3a7755c1a4410 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -78,10 +78,10 @@ extern int __get_user_bad(void); int __ret_gu; \ register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ __chk_user_ptr(ptr); \ - asm volatile("call __" #fn "_%c4" \ + asm volatile("call __" #fn "_%c[size]" \ : "=a" (__ret_gu), "=r" (__val_gu), \ ASM_CALL_CONSTRAINT \ - : "0" (ptr), "i" (sizeof(*(ptr)))); \ + : "0" (ptr), [size] "i" (sizeof(*(ptr)))); \ instrument_get_user(__val_gu); \ (x) = (__force __typeof__(*(ptr))) __val_gu; \ __builtin_expect(__ret_gu, 0); \ diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S index f6aad480febd3..6913fbce6544f 100644 --- a/arch/x86/lib/getuser.S +++ b/arch/x86/lib/getuser.S @@ -44,7 +44,11 @@ or %rdx, %rax .else cmp $TASK_SIZE_MAX-\size+1, %eax +.if \size != 8 jae .Lbad_get_user +.else + jae .Lbad_get_user_8 +.endif sbb %edx, %edx /* array_index_mask_nospec() */ and %edx, %eax .endif @@ -154,7 +158,7 @@ SYM_CODE_END(__get_user_handle_exception) #ifdef CONFIG_X86_32 SYM_CODE_START_LOCAL(__get_user_8_handle_exception) ASM_CLAC -bad_get_user_8: +.Lbad_get_user_8: xor %edx,%edx xor %ecx,%ecx mov $(-EFAULT),%_ASM_AX