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x86/uaccess: Fix missed zeroing of ia32 u64 get_user() range checking

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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@mail.gmail.com
Fixes: b19b74bc99 ("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
This commit is contained in:
Kees Cook 2024-06-10 14:02:27 -07:00 committed by Dave Hansen
parent c625dabbf1
commit 8c860ed825
2 changed files with 7 additions and 3 deletions
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4
arch/x86/include/asm/uaccess.h
View file

@ -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); \

6
arch/x86/lib/getuser.S
View file

@ -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