x86/uaccess: Fix missed zeroing of ia32 u64 get_user() range checking
PATCH 1/1 x86/uaccess: Fix missed zeroing of ia32 u64 get_user() range checking
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)---
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Qiuxu Zhuo <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Masahiro Yamada <[email protected]>
--- arch/x86/include/asm/uaccess.h | 4 ++-- arch/x86/lib/getuser.S | 6 +++++- 2 files changed, 7 insertions(+), 3 deletions(-)
arch/x86/include/asm/uaccess.h +2 -2
@@ -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); \
arch/x86/lib/getuser.S +5 -1
@@ -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
Signature · 1 line
2.34.1
Quoted 21 lines · Kees Cook
When reworking the range checking for
get_user(), theget_user_8()case on 32-bit wasn't zeroing the high register. (The jump tobad_get_user_8was 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)Reported-by David Gow <[email protected]>Closes https://lore.kernel.org/all/CABVgOSn=tb=Lj9SxHuT4_9MTjjKVxsq-ikdXC4kGHO4CfKVmGQ@mail.gmail.com open hereFixes b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()")Signed-off-by Kees Cook <[email protected]>
Quoted 15 lines
---
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Qiuxu Zhuo <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Masahiro Yamada <[email protected]>
---
Thanks: this fixes it here, both under qemu and on real hardware.
-- David
Quoted 34 lines · Kees Cook
When reworking the range checking for
get_user(), theget_user_8()case on 32-bit wasn't zeroing the high register. (The jump tobad_get_user_8was 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)Reported-by David Gow <[email protected]>Closes https://lore.kernel.org/all/CABVgOSn=tb=Lj9SxHuT4_9MTjjKVxsq-ikdXC4kGHO4CfKVmGQ@mail.gmail.com open hereFixes b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()")Signed-off-by Kees Cook <[email protected]>---
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Qiuxu Zhuo <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Quoted 5 lines
--- arch/x86/include/asm/uaccess.h | 4 ++-- arch/x86/lib/getuser.S | 6 +++++- 2 files changed, 7 insertions(+), 3 deletions(-)
Hi,
This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree.
You are receiving this message because of the following common error(s) as indicated below:
- You have marked a patch with a "Fixes:" tag for a commit that is in an older released kernel, yet you do not have a cc: stable line in the signed-off-by area at all, which means that the patch will not be applied to any older kernel releases. To properly fix this, please follow the documented rules in the Documentation/process/stable-kernel-rules.rst file for how to resolve this.
If you wish to discuss this problem further, or you have questions about how to resolve this issue, please feel free to respond to this email and Greg will reply once he has dug out from the pending patches received from other developers.
thanks,
greg k-h's patch email bot
Quoted 77 lines
From: Kees Cook <[email protected]>
[...]
Subject: [PATCH] x86/uaccess: Fix missed zeroing of ia32 u64get_user()range checkingWhen reworking the range checking for
get_user(), theget_user_8()case on 32-bit wasn't zeroing the high register. (The jump tobad_get_user_8was 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)Reported-by David Gow <[email protected]>Fixes b19b74bc99b1 ("x86/mm: Rework address range check in get_user()and
put_user()")Signed-off-by Kees Cook <[email protected]>[...]arch/x86/include/asm/uaccess.h | 4 ++-- arch/x86/lib/getuser.S | 6 +++++- 2 files changed, 7 insertions(+), 3 deletions(-)(quoted diff) +0
-0
b/arch/x86/include/asm/uaccess.hindex0f9bab92a43d..3a7755c1a441100644arch/x86/include/asm/uaccess.h +2
-2@@ -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); \ arch/x86/include/asm/uaccess.h +0
-0(x) = (__force __typeof__(*(ptr))) __val_gu; \__builtin_expect (__ret_gu,0 ); \arch/x86/lib/getuser.S index renamed from arch/x86/lib/getuser.S +0
-0
10d5ed8b5990..a1cb3a4e6742100644arch/x86/lib/getuser.S +5
-2@@ -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 --
Quoted 1 line
2.34.1
LGTM. Thanks!
Quoted 4 lines · Kees Cook
When reworking the range checking for
get_user(), theget_user_8()case on 32-bit wasn't zeroing the high register. (The jump tobad_get_user_8was accidentally dropped.) Restore the correct error handling destination (and rename the jump to using the expected ".L" prefix).
Oh. My bad.
Signature · 1 line
Kiryl Shutsemau / Kirill A. Shutemov