This is a note to let you know that I've just added the patch titled
x86/uaccess: Fix missed zeroing of ia32 u64 get_user() range checking
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-uaccess-fix-missed-zeroing-of-ia32-u64-get_user-.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7ab098cc736d580bb6cbc817254078874bced3a5
Author: Kees Cook <kees@xxxxxxxxxx>
Date: Mon Jun 10 14:02:27 2024 -0700
x86/uaccess: Fix missed zeroing of ia32 u64 get_user() range checking
[ 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-ikdXC4kGHO4CfKVmGQ@xxxxxxxxxxxxxx
Fixes: b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()")
Reported-by: David Gow <davidgow@xxxxxxxxxx>
Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Tested-by: David Gow <davidgow@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20240610210213.work.143-kees%40kernel.org
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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
